Red Hat 2.x Developer Toolset User Guide
Διαφήμιση
Διαφήμιση
Red Hat Developer Toolset 2.x
User Guide
Installing and Using Red Hat Developer Toolset
Edition 1
Jaromír Hradílek
Matt Newsome
Jaromír Hradílek Jacquelynn East
Red Hat Developer Toolset 2.x User Guide
Installing and Using Red Hat Developer Toolset
Edition 1
Jaromír Hradílek
Red Hat Engineering Content Services [email protected]
Jacquelynn East
Red Hat Engineering Content Services [email protected]
Matt Newsome
Red Hat Sof tware Engineering [email protected]
Legal Notice
Copyright 2013 Red Hat, Inc. This document is licensed by Red Hat under the Creative Commons
Attribution-ShareAlike 3.0 Unported License. If you distribute this document, or a modified version of it, you must provide attribution to Red Hat, Inc. and provide a link to the original. If the document is modified, all Red Hat trademarks must be removed. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux is the registered trademark of Linus Torvalds in the United States and other countries. Java is a registered trademark of Oracle and/or its affiliates. XFS is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries. MySQL is a registered trademark of MySQL AB in the United States, the European Union and other countries. Node.js is an official trademark of Joyent.
Red Hat Software Collections is not formally related to or endorsed by the official Joyent Node.js open source or commercial project. The OpenStack Word Mark and OpenStack Logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United
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Keywords
Abstract
Red Hat Developer Toolset is a Red Hat offering for developers on the Red Hat Enterprise Linux platform.
The Red Hat Developer Toolset User Guide provides an overview of this product, explains how to invoke and use the Developer Toolset versions of the tools, and links to resources with more in-depth information.
Table of Contents
2. Getting Help and Giving Feedback
1.1. About Red Hat Developer Toolset
1.4. Getting Access to Red Hat Developer Toolset
1.4.2. Using Red Hat Subscription Management
1.5. Installing Red Hat Developer Toolset
1.5.1. Installing All Available Components
1.5.2. Installing Individual Package Groups
1.5.3. Installing Optional Packages
1.5.4. Installing Debugging Information
1.6. Updating Red Hat Developer Toolset
1.6.1. Updating to a Minor Version
1.6.2. Updating to a Major Version
1.7. Uninstalling Red Hat Developer Toolset
2.1.1. Building Eclipse from the Source RPM Packages
2.2.1. Using the Red Hat Developer Toolset Toolchain
2.2.2. Using the Red Hat Enterprise Linux Toolchain
3.1.1. Installing the C Compiler
3.2.1. Installing the C++ Compiler
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Red Hat Developer Toolset 2.x User Guide
3.3.1. Installing the Fortran Compiler
3.3.2. Using the Fortran Compiler
3.3.3. Running a Fortran Program
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7.1. Installing the GNU Debugger
7.2. Preparing a Program for Debugging
Compiling Programs with Debugging Information
Installing Debugging Information for Existing Packages
7.7. Displaying Current Values
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8.2.1. Redirecting Output to a File
8.2.2. Tracing Selected System Calls
13.2.1. Using Dyninst with SystemTap
13.2.2. Using Dyninst as a Stand-alone Application
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Red Hat Developer Toolset 2.x User Guide
16.1. Gathering Required Information
Account and Contact Information
16.3. Re-opening a Service Request
A.1.1. Changes Since Red Hat Enterprise Linux 6.4
A.2.1. Changes Since Red Hat Developer Toolset 1.1
A.2.1.2. General Improvements and Changes
Compiling Extremely Large Functions
New -fira-hoist-pressure Option
New -floop-nest-optimize Option
Hot and Cold Attributes on Labels
A.2.1.3. Debugging Enhancements
Experimental C++ Features from an Upcoming Standard
Dynamic Initialization of Thread-local Variables
Floating Point Numbers with “q” as Exponential
GFORTRAN_TMPDIR Environment Variable
A.2.1.6. x86-specific Improvements
New Built-in Functions to Detect Run-time CPU Type and ISA
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Transactions Using Transactional Synchronization Extensions
Support for AMD Family 15h Processors
Support for AMD Family 16h Processors
A.2.2. Changes Since Red Hat Enterprise Linux 6.4 and 5.9
A.2.2.1.3. Parallelism and Concurrency
C++11 Types and GCC Built-ins for Atomic Memory Access
A.2.2.1.4. Architecture-specific Options
A.2.2.1.5. Link-time Optimization
A.2.2.2. Language Compatibility
Visibility of Template Instantiations
Taking the Address of Temporary
A.2.2.2.4.2. Compatibility Changes
A.2.2.2.4.3. Fortran 2003 Features
A.2.2.2.4.4. Fortran 2003 Compatibility
A.2.2.2.4.5. Fortran 2008 Features
A.2.2.2.4.6. Fortran 2008 Compatibility
A.2.2.2.4.7. Fortran 77 Compatibility
A.2.2.4. Debugging Compatibility
Changes Since Red Hat Enterprise Linux 6.4
Changes Since Red Hat Enterprise Linux 5.9
A.3.1.2. Compatibility Changes
Changes Since Red Hat Enterprise Linux 6.4
Changes Since Red Hat Enterprise Linux 5.9
Changes Since Red Hat Enterprise Linux 6.4
Changes Since Red Hat Enterprise Linux 5.9
Changes Since Red Hat Developer Toolset 1.1
Changes Since Red Hat Enterprise Linux 6.4
Changes Since Red Hat Enterprise Linux 5.9
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A.3.3.2. Compatibility Changes
Changes Since Red Hat Enterprise Linux 5.9
A.4.1. Changes Since Red Hat Developer Toolset 1.1
A.4.2. Changes Since Red Hat Enterprise Linux 6.4
A.4.3. Changes Since Red Hat Enterprise Linux 5.9
A.5.1. Changes Since Red Hat Developer Toolset 1.1
A.6.1. Changes Since Red Hat Developer Toolset 1.1
A.6.2. Changes Since Red Hat Enterprise Linux 6.4
A.6.3. Changes Since Red Hat Enterprise Linux 5.9
A.7.1. Changes Since Red Hat Enterprise Linux 6.4 and 5.9
A.8.1. Changes Since Red Hat Developer Toolset 1.1
A.9.1. Changes Since Red Hat Developer Toolset 1.1
A.9.2. Changes Since Red Hat Enterprise Linux 5.9
A.10.1. Changes Since Red Hat Developer Toolset 1.1
A.10.2. Changes Since Red Hat Enterprise Linux 5.9
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Red Hat Developer Toolset 2.x User Guide
Preface
1. Document Conventions
This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information.
In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts set. The
Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not, alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later include the Liberation
Fonts set by default.
1.1. Typographic Conventions
Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows.
Mono-spaced Bold
Used to highlight system input, including shell commands, file names and paths. Also used to highlight keys and key combinations. For example:
To see the contents of the file my_next_bestselling_novel in your current working directory, enter the cat my_next_bestselling_novel command at the shell prompt and press Enter to execute the command.
The above includes a file name, a shell command and a key, all presented in mono-spaced bold and all distinguishable thanks to context.
Key combinations can be distinguished from an individual key by the plus sign that connects each part of a key combination. For example:
Press Enter to execute the command.
Press Ctrl+Alt+F2 to switch to a virtual terminal.
The first example highlights a particular key to press. The second example highlights a key combination: a set of three keys pressed simultaneously.
If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in mono-spaced bold. For example:
File-related classes include filesystem for file systems, file for files, and dir for directories. Each class has its own associated set of permissions.
Proportional Bold
This denotes words or phrases encountered on a system, including application names; dialog box text; labeled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example:
Choose System → Preferences → Mouse from the main menu bar to launch Mouse
Preferences. In the Buttons tab, select the Left-handed mouse check box and click
Close to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand).
To insert a special character into a gedit file, choose Applications → Accessories →
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Preface
Character Map from the main menu bar. Next, choose Search → Find… from the
Character Map menu bar, type the name of the character in the Search field and click
Next. The character you sought will be highlighted in the Character T able. Double-click this highlighted character to place it in the Text to copy field and then click the Copy button. Now switch back to your document and choose Edit → Paste from the gedit menu bar.
The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in proportional bold and all distinguishable by context.
Mono-spaced Bold Italic or Proportional Bold Italic
Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example:
To connect to a remote machine using ssh, type ssh username@domain.name at a shell prompt. If the remote machine is example.com and your username on that machine is john, type ssh [email protected].
The mount -o remount file-system command remounts the named file system. For example, to remount the /home file system, the command is mount -o remount /home.
To see the version of a currently installed package, use the rpm -q package command. It will return a result as follows: package-version-release.
Note the words in bold italics above — username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system.
Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example:
Publican is a DocBook publishing system.
1.2. Pull-quote Conventions
Terminal output and source code listings are set off visually from the surrounding text.
Output sent to a terminal is set in mono-spaced roman and presented thus: books Desktop documentation drafts mss photos stuff svn books_tests Desktop1 downloads images notes scripts svgs
Source-code listings are also set in mono-spaced roman but add syntax highlighting as follows:
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Red Hat Developer Toolset 2.x User Guide static int kvm_vm_ioctl_deassign_device( struct kvm *kvm, struct kvm_assigned_pci_dev *assigned_dev)
{ int r = 0; struct kvm_assigned_dev_kernel *match;
mutex_lock(&kvm->lock);
match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head,
assigned_dev->assigned_dev_id); if (!match) {
printk(KERN_INFO "%s: device hasn't been assigned before, "
"so cannot be deassigned \n " , __func__);
r = -EINVAL; goto out;
}
kvm_deassign_device(kvm, match);
kvm_free_assigned_device(kvm, match); out:
mutex_unlock(&kvm->lock); return r;
}
1.3. Notes and Warnings
Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.
Note
Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier.
Important
Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring a box labeled 'Important' will not cause data loss but may cause irritation and frustration.
Warning
Warnings should not be ignored. Ignoring warnings will most likely cause data loss.
2. Getting Help and Giving Feedback
2.1. Do You Need Help?
If you experience difficulty with a procedure described in this documentation, visit the Red Hat Customer
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Preface
Portal at http://access.redhat.com
. Through the customer portal, you can: search or browse through a knowledgebase of technical support articles about Red Hat products.
submit a support case to Red Hat Global Support Services (GSS).
access other product documentation.
Red Hat also hosts a large number of electronic mailing lists for discussion of Red Hat software and technology. You can find a list of publicly available mailing lists at https://www.redhat.com/mailman/listinfo .
Click on the name of any mailing list to subscribe to that list or to access the list archives.
2.2. We Need Feedback
If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you. Please submit a report in Bugzilla: http://bugzilla.redhat.com/ against the product Red Hat Developer Toolset.
When submitting a bug report, be sure to mention the manual's identifier: doc-User_Guide
If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily.
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Red Hat Developer Toolset 2.x User Guide
Part I. Introduction
Chapter 1. Red Hat Developer Toolset
Chapter 1. Red Hat Developer Toolset
1.1. About Red Hat Developer Toolset
Red Hat Developer Toolset is a Red Hat offering for developers on the Red Hat Enterprise Linux platform, and provides a complete set of development and performance analysis tools that can be installed and used on multiple versions of Red Hat Enterprise Linux. Executables built with the Red Hat
Developer Toolset toolchain can then also be deployed and run on multiple versions of Red Hat
Enterprise Linux. For detailed compatibility information, see Section 1.3, “Compatibility”
.
Critically, Red Hat Developer Toolset does not replace the default system tools provided with Red Hat
Enterprise Linux 5 or 6 when installed on those platforms. Instead, a parallel set of developer tools provides an alternative, newer version of those tools for optional use by developers. The default compiler and debugger, for example, remain those provided by the base Red Hat Enterprise Linux system.
Table 1.1. Red Hat Developer Toolset Components
Name Version Description
Eclipse 4.3.0
An integrated development environment for the graphical
GCC binutils elfutils dwz
GDB strace
4.8.1
2.23.52
0.155
0.11
7.6
4.7
A portable compiler suite with support for C, C++, and
Fortran.
A collection of binary tools and other utilities to inspect and manipulate object files and binaries.
A collection of binary tools and other utilities to inspect and manipulate ELF files.
A tool to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size.
A command line debugger for programs written in C, C++, and Fortran.
A debugging tool to monitor system calls that a program uses and signals it receives.
memstomp
SystemTap
Valgrind
0.1.4
2.1
3.8.1
A debugging tool to identify calls to library functions with overlapping memory regions that are not allowed by various standards.
A tracing and probing tool to monitor the activities of the entire system without the need to instrument, recompile, install, and reboot.
An instrumentation framework and a number of tools to profile applications in order to detect memory errors, identify memory management problems, and report any use of improper arguments in system calls.
OProfile 0.9.8
A system-wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system.
Dyninst 8.0
A library for instrumenting and working with user-space executables during their execution.
If yo u intend to d evelo p ap p licatio ns fo r Red Hat JBo ss Mid d leware o r req uire sup p o rt fo r O p enShift To o ls, it is reco mmend ed that yo u use Red Hat JBo ss Develo p er Stud io .
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Red Hat Developer Toolset 2.x User Guide
Red Hat Developer Toolset differs from “ Technology Preview ” compiler releases previously supplied in
Red Hat Enterprise Linux in two important respects:
1. Red Hat Developer Toolset can be used on multiple major and minor releases of Red Hat
Enterprise Linux, as detailed in Section 1.3, “Compatibility”
.
2. Unlike Technology Preview compilers and other tools shipped in earlier Red Hat Enterprise Linux,
Red Hat Developer Toolset is fully supported under Red Hat Enterprise Linux Subscription Level
Agreements, is functionally complete, and is intended for production use.
Important bug fixes and security errata are issued to Red Hat Developer Toolset subscribers in a similar manner to Red Hat Enterprise Linux for two years from the release of each major version release. New major versions of Red Hat Developer Toolset is released annually, providing significant updates for existing components and adding major new components. A single minor release, issued six months after each new major version release, provides a smaller update of bug fixes, security errata, and new minor components.
Additionally, the Red Hat Enterprise Linux Application Compatibility Specification also applies to Red Hat
Developer Toolset (subject to some constraints on the use of newer C++11 language features, detailed
in Section A.2.2.3, “ABI Compatibility”
).
Important
Applications and libraries provided by Red Hat Developer Toolset do not replace the Red Hat
Enterprise Linux system versions, nor are they used in preference to the system versions. Using a framework called Software Collections, an additional set of developer tools is installed into the /opt directory and is explicitly enabled by the user on demand using the supplied scl utility.
1.2. Main Features
The Red Hat Developer Toolset version of the GNU Compiler Collection (GCC) provides the following features:
A new register allocator (LRA) has been added, improving code performance.
A fast memory error detector called AddressSanitizer has been added.
A fast data race detector called ThreadSanitizer has been added.
Extremely large functions can now be compiled faster using less memory.
A new general optimization level has been introduced.
GCC diagnostic messages now highlight the exact problem source code.
Various new optimization options have been added.
DWARF4 is now used as the default debug format.
GCC now fully implements the C++11 language standard.
C++11 library support has been extended though is still experimental.
GCC now supports dynamic initialization of thread-local variables.
Support has been added for Intel FXSR, XSAVE, and XSAVEOPT instructions.
New built-in functions added to detect run-time Intel CPU Type and ISA.
Intel function multi-versioning support added.
Intel RTM/HLE intrinsics, built-ins, and code generation have been added.
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Chapter 1. Red Hat Developer Toolset
Transactions (the -fgnu-tm option) can now be run using Intel TSX extensions.
Support for AMD family 15h and 16h processors has been added.
Various Fortran changes have been included.
The version of the GNU Debugger (GDB) included in Red Hat Developer Toolset provides the following features:
Improved and expanded support for Python scripting.
Improved handling of C++ debugee executables.
Improved inferior control commands.
Improved support for ambiguous line specifications.
Improved tracepoint support.
Multi-program debugging.
Additionally, the Red Hat Developer Toolset version of binutils provides these features:
The new gold linker, which is smaller and faster than ld. Note that gold is not the default linker and must be explicitly enabled by using the alternatives command.
Support for link-time optimization (LTO) in conjunction with GCC.
Support for build-IDs, unique numbers to identify executables.
Support for the IFUNC and UNIQUE symbols that are used by glibc to improve performance. Due to dependencies on a particular version of the glibc library, these symbols are only available on
Red Hat Enterprise Linux 6.
Compressed debug sections for smaller debug info files.
1.3. Compatibility
Red Hat Developer Toolset 2.0 is available for Red Hat Enterprise Linux 5 and 6, both for 32-bit and 64-
bit Intel and AMD architectures. Figure 1.1, “Red Hat Developer Toolset 2.0 Compatibility Matrix”
illustrates the support for binaries built with Red Hat Developer Toolset on a certain version of Red Hat
Enterprise Linux when those binaries are run on various other versions of this system.
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Red Hat Developer Toolset 2.x User Guide
Figure 1.1. Red Hat Developer Toolset 2.0 Compatibility Matrix
1.4. Getting Access to Red Hat Developer Toolset
Red Hat Developer Toolset is an offering that is distributed as part of the developer subscriptions listed
in Table 1.2, “Subscriptions That Provide Red Hat Developer Toolset”
. Depending on the subscription management service with which you registered your Red Hat Enterprise Linux system, you can either enable Red Hat Developer Toolset by using the Red Hat Subscription Management, or by using RHN
Classic.
For detailed instructions on how to enable Red Hat Developer Toolset using RHN Classic or Red Hat
Subscription Management, see the respective section below. For information on how to register your system with one of these subscription management services, see the Red Hat Subscription
Management Guide.
Important
If you are running a version of Red Hat Enterprise Linux prior to 5.9 or 6.4, you will be unable to download Red Hat Developer Toolset through Red Hat Subscription Management. To obtain Red
Hat Developer Toolset, you will need to either update to Red Hat Enterprise Linux 5.9 or 6.4, or register your system with RHN Classic. For more information, see https://access.redhat.com/site/solutions/129003 .
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Chapter 1. Red Hat Developer Toolset
Table 1.2. Subscriptions That Provide Red Hat Developer Toolset
SKU
RH2282403
RH2264664
RH2262474
RH3482727
RH3413336
RH3414706
RH3474212
RH3437268
SER0402
SER0403
Subscription Name
Red Hat Enterprise Linux Developer Support, Professional
Red Hat Enterprise Linux Developer Support, Enterprise
Red Hat Enterprise Linux Developer Suite
Red Hat Enterprise Linux Developer Workstation, Professional
Red Hat Enterprise Linux Developer Workstation, Enterprise
30 day Self-Supported Red Hat Enterprise Linux Developer Workstation
Evaluation
60 day Supported Red Hat Enterprise Linux Developer Workstation Evaluation
90 day Supported Red Hat Enterprise Linux Developer Workstation Evaluation
1-year Unsupported Partner Evaluation Red Hat Enterprise Linux
1-year Unsupported Red Hat Advanced Partner Subscription
1.4.1. Using RHN Classic
If your system is registered with RHN Classic, complete the following steps to subscribe to Red Hat
Developer Toolset:
1. Display a list of all channels that are available to you in order to determine the exact name of the
Red Hat Developer Toolset channel. To do so, type the following at a shell prompt as root:
rhn-channel --available-channels
The name of the channel depends on the specific version of Red Hat Enterprise Linux you are using and is in the rhel-architecture-variant-dts2-version format, where architecture is the system's CPU architecture (x86_64 or i386), variant is the Red Hat Enterprise Linux system variant (server or workstation), and version is the Red Hat Enterprise Linux system version (5 or 6).
2. Subscribe the system to the Red Hat Developer Toolset channel by running the following command as root:
rhn-channel --add --channel=channel_name
Replace channel_name with the name you determined in the previous step.
3. To verify the list of channels you are subscribed to, at any time, run as root:
rhn-channel --list
Classic, see the Red Hat Subscription Management Guide.
1.4.2. Using Red Hat Subscription Management
If your system is registered with Red Hat Subscription Management, complete the following steps to attach a subscription that provides access to the repository for Red Hat Developer Toolset, and then enable that repository:
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Red Hat Developer Toolset 2.x User Guide
1. Display a list of all subscriptions that are available for your system to determine the pool ID of a subscription that provides Red Hat Developer Toolset. To do so, type the following at a shell prompt as root:
subscription-manager list --available
For each available subscription, this command displays its name, unique identifier, expiration date, and other details related to your subscription. The pool ID is listed on a line beginning with Pool
Id.
For a complete list of subscriptions that provide access to Red Hat Developer Toolset, see
Table 1.2, “Subscriptions That Provide Red Hat Developer Toolset”
.
2. Attach the appropriate subscription to your system by running the following command as root:
subscription-manager subscribe --pool=pool_id
Replace pool_id with the pool ID you determined in the previous step. To verify the list of subscriptions your system has currently attached, at any time, run as root:
subscription-manager list --consumed
3. Display a list of available Yum repositories to retrieve repository metadata and to determine the exact name of the Red Hat Developer Toolset repositories. As root, type:
yum repolist all
The repository names depend on the specific version of Red Hat Enterprise Linux you are using, and are in the following format: rhel-variant-dts2-version-rpms rhel-variant-dts2-version-debug-rpms rhel-variant-dts2-version-source-rpms
Replace variant with the Red Hat Enterprise Linux system variant (server or workstation), and version with the Red Hat Enterprise Linux system version (5 or 6).
4. Enable the appropriate repository. On Red Hat Enterprise Linux 6, you can do so by running the following command as root:
yum-config-manager --enable repository
On Red Hat Enterprise Linux 5, which does not support the yum-config-manager tool, edit the
/etc/yum .repos.d/redhat.repo file, locate the relevant [repository] section, and set the value of the enabled option to 1: enabled = 1
Once the subscription is attached to the system, you can install Red Hat Developer Toolset as
described in Section 1.5, “Installing Red Hat Developer Toolset”
. For more information on how to register your system using Red Hat Subscription Management and associate it with subscriptions, see the Red
Hat Subscription Management Guide.
1.5. Installing Red Hat Developer Toolset
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Chapter 1. Red Hat Developer Toolset
Red Hat Developer Toolset is distributed as a collection of RPM packages that can be installed, updated, uninstalled, and inspected by using the standard package management tools that are included in Red Hat Enterprise Linux. Note that a valid subscription is required in order to install Red Hat
Developer Toolset on your system. For detailed instructions on how to associate your system with an
appropriate subscription and get access to the product, see Section 1.4, “Getting Access to Red Hat
Important
Before installing Red Hat Developer Toolset on a system that is already running the previous version of the product, make sure that the devtoolset-1.1-gcc-debuginfo is not installed. To uninstall this package from the system, type the following at a shell prompt as root:
yum remove devtoolset-1.1-gcc-debuginfo
Important
After installing Red Hat Developer Toolset, it is recommended to apply all available Red Hat
Enterprise Linux errata updates to enable all Red Hat Developer Toolset features and apply fixes that may otherwise impact the tools or built code.
1.5.1. Installing All Available Components
To install all components that are included in this product, install the devtoolset-2 package by typing the following at a shell prompt as root:
yum install devtoolset-2
This installs the Eclipse development environment, all development, debugging, and performance monitoring tools, the scl utility and other dependent packages to the system. Alternatively, you can
1.5.2. Installing Individual Package Groups
To make it easier to install only certain components such as the integrated development environment or the software development toolchain, Red Hat Developer Toolset is distributed with a number of meta
packages that allow you to install selected package groups as described in Table 1.3, “Red Hat
Developer Toolset Meta Packages” .
Table 1.3. Red Hat Developer Toolset Meta Packages
Package Name
devtoolset-2-ide devtoolset-2-perftools devtoolset-2-toolchain
Description Installed Components
Integrated Development
Environment
Performance monitoring tools
Eclipse
SystemTap, Valgrind, OProfile,
Dyninst
Development and debugging tools GCC, GDB, binutils, elfutils, dwz, memstomp, strace
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Red Hat Developer Toolset 2.x User Guide
To install any of these meta packages, type the following at a shell prompt as root:
yum install package_name...
Replace package_name with a space-separated list of meta packages you want to install. For example, to install only the Eclipse development environment and packages that depend on it, type as root:
~]# yum install devtoolset-2-ide
1.5.3. Installing Optional Packages
Red Hat Developer Toolset is distributed with a number of optional packages that are not installed by default. To list all Red Hat Developer Toolset packages that are available to you but not installed on your system, type the following command at a shell prompt:
yum list available devtoolset-2-\*
To install any of these optional packages, run as root:
yum install package_name...
Replace package_name with a space-separated list of packages that you want to install. For example, to install the devtoolset-2-gdb-gdbserver and devtoolset-2-gdb-doc packages, type:
~]# yum install devtoolset-2-gdb-gdbserver devtoolset-2-gdb-doc
Important
The devtoolset-2-gcc-plugin-devel package depends on the mpfr-devel package, which is only available in the Optional channel. For detailed instructions on how to subscribe your system to this channel, see the relevant Knowledge article on the Customer Portal .
1.5.4. Installing Debugging Information
To install debugging information for any of the Red Hat Developer Toolset packages, make sure that the
yum-utils package is installed and run the following command as root:
debuginfo-install package_name
For example, to install debugging information for the devtoolset-2-dwz package, type:
~]# debuginfo-install devtoolset-2-dwz
Note that in order to use this command, you need to have access to the repository with these packages.
If your system is registered with Red Hat Subscription Management, enable the rhel-variant-
dts2-version-debug-rpm s repository as described in
Section 1.4.2, “Using Red Hat Subscription
Management” . If your system is registered with RHN Classic, subscribe the system to the
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Chapter 1. Red Hat Developer Toolset
rhel-architecture-variant-version-debuginfo channel as described in
RHN Classic” . For more information on how to get access to debuginfo packages, see
https://access.redhat.com/site/solutions/9907 .
1.6. Updating Red Hat Developer Toolset
1.6.1. Updating to a Minor Version
When a new minor version of Red Hat Developer Toolset is available, run the following command as
root to update your Red Hat Enterprise Linux installation:
yum update
This updates all packages on your Red Hat Enterprise Linux system, including the Red Hat Developer
Toolset versions the Eclipse development environment, development, debugging, and performance monitoring tools, the scl utility and other dependent packages.
Important
Use of Red Hat Developer Toolset requires the removal of any earlier pre-release versions of this product. Additionally, it is not possible to update to Red Hat Developer Toolset 2.0 from a pre-release version of Red Hat Developer Toolset, including beta releases. If you have previously installed any pre-release version of Red Hat Developer Toolset, uninstall it from your system as
described in Section 1.7, “Uninstalling Red Hat Developer Toolset”
and install the new version as
documented in Section 1.5, “Installing Red Hat Developer Toolset”
.
1.6.2. Updating to a Major Version
When a new major version of Red Hat Developer Toolset is available, you can install it in parallel with the previous version of the product. For detailed instructions on how to install Red Hat Developer
Toolset on your system, see Section 1.5, “Installing Red Hat Developer Toolset”
.
1.7. Uninstalling Red Hat Developer Toolset
To uninstall Red Hat Developer Toolset packages from your system, type the following at a shell prompt as root:
yum remove devtoolset-2\*
This removes the GNU Compiler Collection, GNU Debugger, binutils, and other packages that are part of
Red Hat Developer Toolset from the system. To uninstall the scl utility as well, type as root:
yum remove scl-utils\*
Note that uninstallation of the tools provided by Red Hat Developer Toolset does not affect the Red Hat
Enterprise Linux system versions of these tools.
For information on how to uninstall Red Hat Developer Toolset 1.1, see the Red Hat Developer Toolset
1.1 User Guide .
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Red Hat Developer Toolset 2.x User Guide
1.8. Additional Resources
For more information about Red Hat Developer Toolset and Red Hat Enterprise Linux, see the resources listed below.
Online Documentation
Red Hat Subscription Management Guide — The Red Hat Subscription Management Guide provides detailed information on how to manage subscriptions on Red Hat Enterprise Linux.
Red Hat Developer Toolset 2.0 Release Notes — The Release Notes for Red Hat Developer Toolset
2.0 contain more information about this product.
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides more information on the Eclipse IDE, libraries and runtime support, compiling and building, debugging, and profiling on this system.
Red Hat Enterprise Linux 6 Installation Guide — The Installation Guide for Red Hat Enterprise Linux
6 explains how to obtain, install, and update the system.
Red Hat Enterprise Linux 5 Installation Guide — The Installation Guide for Red Hat Enterprise Linux
5 explains how to obtain, install, and update the system.
Red Hat Enterprise Linux 6 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 6 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 6.
Red Hat Enterprise Linux 5 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 5 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 5.
See Also
Appendix A, Changes in Version 2.0
provides a comprehensive list of changes and improvements over the Red Hat Enterprise Linux system versions of the GNU Compiler Collection, GNU Debugger, and binutils, as well as information about the language, ABI, and debugging compatibility.
22
Part II. Integrated Development Environments
Part II. Integrated Development Environments
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Red Hat Developer Toolset 2.x User Guide
Chapter 2. Eclipse
Eclipse is a powerful development environment that provides tools for each phase of the development process. It integrates a variety of disparate tools into a unified environment to create a rich development experience, provides a fully configurable user interface, and features a pluggable architecture that allows for extension in a variety of ways. For instance, the Valgrind plug-in allows programmers to perform memory profiling, otherwise performed on the command line, through the Eclipse user interface.
Figure 2.1. Sample Eclipse Session
Eclipse provides a graphical development environment alternative to traditional interaction with command line tools and as such, it is a welcome alternative to developers who do not want to use the command line interface. The traditional, mostly command line based Linux tools suite (such as gcc or gdb) and
Eclipse offer two distinct approaches to programming.
Red Hat Developer Toolset is distributed with Eclipse 4 .3.0, which is based on the Eclipse
Foundation's 2013 Eclipse 4.3 “Kepler” simultaneous release. Note that if you intend to develop applications for Red Hat JBoss Middleware or require support for OpenShift Tools, it is recommended that you use Red Hat JBoss Developer Studio .
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Chapter 2. Eclipse
Table 2.1. Eclipse Components Included in Red Hat Developer Toolset
Package Description
devtoolset-2-eclipse-cdt devtoolset-2-eclipse-emf devtoolset-2-eclipse-gef devtoolset-2-eclipse-rse devtoolset-2-eclipse-jgit devtoolset-2-eclipse-egit devtoolset-2-eclipse-mylyn devtoolset-2-eclipse-linuxtools devtoolset-2-eclipse-changelog
devtoolset-2-eclipse-gcov devtoolset-2-eclipse-gprof
The C/C++ Development Tooling (CDT), which provides features and plug-ins for development in C and C++.
The Eclipse Modeling Framework (EMF), which allows you to build applications based on a structured data model.
The Graphical Editing Framework (GEF), which allows you to create a rich graphical editor from an existing application model.
The Remote System Explorer (RSE) framework, which allows you to work with remote systems from Eclipse.
JGit, a Java implementation of the Git revision control system.
EGit, a team provider for Eclipse that provides features and plugins for interaction with Git repositories.
Mylyn, a task management system for Eclipse.
A meta package for Linux-specific Eclipse plug-ins.
The ChangeLog plug-ins, which allows you to create and maintain changelog files.
The GCov plug-in, which integrates the GCov test coverage program with Eclipse.
The Gprof plug-in, which integrates the Gprof performance analysis utility with Eclipse.
The Man Page plug-in, which allows you to view manual pages in
Eclipse.
The OProfile plug-in, which integrates OProfile with Eclipse.
devtoolset-2-eclipse-perf
The Perf plug-in, which integrates the perf tool with Eclipse.
devtoolset-2-eclipse-rpm-editor
devtoolset-2-eclipse-rpmstubby devtoolset-2-eclipse-systemtap
The Eclipse Spec File Editor, which allows you to maintain RPM spec files.
The RPM Stubby plug-in, which allows you to generate RPM spec files.
The SystemTap plug-in, which integrates SystemTap with
Eclipse.
The Valgrind plug-in, which integrates Valgrind with Eclipse.
This p ackag e is installed as a d ep end ency o f devtoolset-2-eclipse-linuxtools.
2.1. Installing Eclipse
In Red Hat Developer Toolset, the Eclipse development environment is provided as a collection of RPM
“Installing Red Hat Developer Toolset” . For a list of available components, see Table 2.1, “Eclipse
Components Included in Red Hat Developer Toolset” .
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Red Hat Developer Toolset 2.x User Guide
Note
The Red Hat Developer Toolset version of Eclipse is only available for Red Hat Enterprise Linux
6 on 32-bit and 64-bit Intel and AMD architectures. This version fully supports C, C++, and Java development, but does not provide support for the Fortran programming language.
2.1.1. Building Eclipse from the Source RPM Packages
It is recommended that you install the Red Hat Developer Toolset version of Eclipse from the official
RPM packages distributed by Red Hat. If, for some reason, you need to build Red Hat Developer Toolset
2.0 Eclipse on Red Hat Enterprise Linux 6 from the supplied source RPM (SRPM) packages, complete the following steps:
1. Install the java-1.7.0-openjdk package from Red Hat Enterprise Linux 6.3 or newer and all its dependencies.
2. Download, build, and install the maven package and all its dependencies from the SRPM packages for Fedora 19.
3. Download, build, and install the tycho package and all its dependencies from the SRPM packages for Fedora 19.
4. Download and build all dependent packages listed in the devtoolset-2-eclipse SRPM package.
5. Download and build the devtoolset-2-eclipse SRPM package.
6. Download and build additional devtoolset-2-eclipse-* SRPM packages.
2.2. Using Eclipse
To start the Red Hat Developer Toolset version of Eclipse, either select Applications →
Programming → DTS Eclipse from the panel, or type the following at a shell prompt:
scl enable devtoolset-2 'eclipse'
During its startup, Eclipse prompts you to select a workspace, that is, a directory in which you want to store your projects. You can either use ~/workspace/, which is the default option, or click the Browse button to browse your file system and select a custom directory. Additionally, you can select the Use
this as the default and do not ask again check box to prevent Eclipse from displaying this dialog box the next time you run this development environment. When you are done, click the OK button to confirm the selection and proceed with the startup.
2.2.1. Using the Red Hat Developer Toolset Toolchain
To use the Red Hat Developer Toolset version of Eclipse with support for the GNU Compiler Collection and binutils from Red Hat Developer Toolset, make sure that the devtoolset-2-toolchain package is
installed and run the application as described in Section 2.2, “Using Eclipse”
. Red Hat Developer Toolset
Eclipse uses the Red Hat Developer Toolset toolchain by default.
For detailed instructions on how to install the devtoolset-2-toolchain package in your system, see
Section 1.5, “Installing Red Hat Developer Toolset”
.
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Chapter 2. Eclipse
Important
If you are working on a project that you previously built with the Red Hat Enterprise Linux version of the GNU Compiler Collection, make sure that you discard all previous build results. To do so, open the project in Eclipse and select Project → Clean from the menu.
2.2.2. Using the Red Hat Enterprise Linux Toolchain
To use the Red Hat Developer Toolset version of Eclipse with support for the toolchain distributed with
Red Hat Enterprise Linux, either uninstall devtoolset-2-gcc, devtoolset-2-binutils, and related packages from your system, or change the configuration of the project to use absolute paths to the Red Hat
Enterprise Linux system versions of gcc, g++, and as.
To uninstall the Red Hat Developer Toolset toolchain from the system, type the following at a shell prompt as root:
yum remove devtoolset-2-gcc\* devtoolset-2-binutils\*
To configure Eclipse to explicitly use the Red Hat Enterprise Linux system versions of the tools for the current project, complete the following steps:
1. In the C/C++ perspective, choose Project → Properties from the main menu bar to open the project properties.
2. In the menu on the left-hand side of the dialog box, click C/C++ Build → Settings.
3. Select the Tool Settings tab.
4. If you are working on a C project: a. select GCC C Compiler or Cross GCC Compiler and change the value of the Command field to:
/usr/bin/gcc b. select GCC C Linker or Cross GCC Linker and change the value of the Command field to:
/usr/bin/gcc c. select GCC Assembler or Cross GCC Assembler and change the value of the
Com m and field to:
/usr/bin/as
If you are working on a C++ project: a. select GCC C++ Compiler or Cross G++ Compiler and change the value of the
Com m and field to:
/usr/bin/g++ b. select GCC C Compiler or Cross GCC Compiler and change the value of the Command field to:
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Red Hat Developer Toolset 2.x User Guide
/usr/bin/gcc c. select GCC C++ Linker or Cross G++ Linker and change the value of the Command field to:
/usr/bin/g++ d. select GCC Assembler or Cross GCC Assembler and change the value of the
Com m and field to:
/usr/bin/as
5. Click the OK button to save the configuration changes.
2.3. Additional Resources
A detailed description of Eclipse and all its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
Eclipse includes a built-in Help system which provides extensive documentation for each integrated feature and tool. This greatly decreases the initial time investment required for new developers to become fluent in its use. The use of this Help section is detailed in the Red Hat Enterprise Linux
Developer Guide linked below.
Online Documentation
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides more information on Eclipse, including a description of the user interface, overview of available development toolkits, or instructions on how to use it to build RPM packages.
See Also
Section A.1, “Changes in Eclipse”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of the Eclipse development environment.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
Chapter 3, GNU Compiler Collection (GCC)
provides information on how to compile programs written in C, C++, and Fortran on the command line.
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Part III. Development Tools
Part III. Development Tools
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Red Hat Developer Toolset 2.x User Guide
Chapter 3. GNU Compiler Collection (GCC)
The GNU Compiler Collection, commonly abbreviated GCC, is a portable compiler suite with support for a wide selection of programming languages.
Red Hat Developer Toolset is distributed with GCC 4 .8. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements, including optimization for various new Intel and AMD processors, support for OpenMP 3.1 and link-time optimization. This version also includes experimental support for the C++11 standard, C++11 atomic types, and Transactional Memory. For a detailed list of changes, see
.
3.1. GNU C Compiler
3.1.1. Installing the C Compiler
In Red Hat Developer Toolset, the GNU C compiler is provided by the devtoolset-2-gcc package and is
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
3.1.2. Using the C Compiler
To compile a C program on the command line, run the gcc compiler as follows:
scl enable devtoolset-2 'gcc -o output_file source_file...'
This creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default.
When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. This way, when you change a single source file, you can recompile only this file without having to compile the entire project.
To compile an object file on the command line, run the following command:
scl enable devtoolset-2 'gcc -o object_file -c source_file'
This creates an object file named object_file. If the -o option is omitted, the compiler creates a file named after the source file with the .o file extension. To link object files together and create a binary file, run:
scl enable devtoolset-2 'gcc -o output_file object_file...'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset gcc as default:
scl enable devtoolset-2 'bash'
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Chapter 3. GNU Compiler Collection (GCC)
Note
To verify the version of gcc you are using at any point, type the following at a shell prompt:
which gcc
Red Hat Developer Toolset's gcc executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset gcc:
gcc -v
Important
Some newer library features are statically linked into applications built with Red Hat Developer
Toolset to support execution on multiple versions of Red Hat Enterprise Linux. This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons.
Example 3.1. Compiling a C Program on the Command Line
Consider a source file named hello.c with the following contents:
#include <stdio.h> int main( int argc, char *argv[]) {
printf( "Hello, World!
\n " ); return 0;
}
To compile this source code on the command line by using the gcc compiler from Red Hat Developer
Toolset, type:
~]$ scl enable devtoolset-2 'gcc -o hello hello.c'
This creates a new binary file called hello in the current working directory.
3.1.3. Running a C Program
When gcc compiles a program, it creates an executable binary file. To run this program on the command line, change to the directory with the executable file and type:
./file_name
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Red Hat Developer Toolset 2.x User Guide
Example 3.2. Running a C Program on the Command Line
Assuming that you have successfully compiled the hello binary file as shown in Example 3.1,
“Compiling a C Program on the Command Line” , you can run it by typing the following at a shell
prompt:
~]$ ./hello
Hello, World!
3.2. GNU C++ Compiler
3.2.1. Installing the C++ Compiler
In Red Hat Developer Toolset, the GNU C++ compiler is provided by the devtoolset-2-gcc-c++ package
and is automatically installed with the devtoolset-2-toolchain package as described in Section 1.5,
“Installing Red Hat Developer Toolset” .
3.2.2. Using the C++ Compiler
To compile a C++ program on the command line, run the g++ compiler as follows:
scl enable devtoolset-2 'g++ -o output_file source_file...'
This creates a binary file named output_file in the current working directory. If the -o option is omitted, the g++ compiler creates a file named a.out by default.
When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. This way, when you change a single source file, you can recompile only this file without having to compile the entire project.
To compile an object file on the command line, run the following command:
scl enable devtoolset-2 'g++ -o object_file -c source_file'
This creates an object file named object_file. If the -o option is omitted, the g++ compiler creates a file named after the source file with the .o file extension. To link object files together and create a binary file, run:
scl enable devtoolset-2 'g++ -o output_file object_file...'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset g++ as default:
scl enable devtoolset-2 'bash'
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Chapter 3. GNU Compiler Collection (GCC)
Note
To verify the version of g++ you are using at any point, type the following at a shell prompt:
which g++
Red Hat Developer Toolset's g++ executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset g++:
g++ -v
Important
Some newer library features are statically linked into applications built with Red Hat Developer
Toolset to support execution on multiple versions of Red Hat Enterprise Linux. This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons.
Example 3.3. Compiling a C++ Program on the Command Line
Consider a source file named hello.cpp with the following contents:
#include <iostream> using namespace std; int main( int argc, char *argv[]) {
cout << "Hello, World!" << endl; return 0;
}
To compile this source code on the command line by using the g++ compiler from Red Hat Developer
Toolset, type:
~]$ scl enable devtoolset-2 'g++ -o hello hello.cpp'
This creates a new binary file called hello in the current working directory.
3.2.3. Running a C++ Program
When g++ compiles a program, it creates an executable binary file. To run this program on the command line, change to the directory with the executable file and type:
./file_name
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Red Hat Developer Toolset 2.x User Guide
Example 3.4 . Running a C++ Program on the Command Line
Assuming that you have successfully compiled the hello binary file as shown in Example 3.3,
“Compiling a C++ Program on the Command Line” , you can run it by typing the following at a shell
prompt:
~]$ ./hello
Hello, World!
3.3. GNU Fortran Compiler
3.3.1. Installing the Fortran Compiler
In Red Hat Developer Toolset, the GNU Fortran compiler is provided by the devtoolset-2-gcc-gfortran
3.3.2. Using the Fortran Compiler
To compile a Fortran program on the command line, run the gfortran compiler as follows:
scl enable devtoolset-2 'gfortran -o output_file source_file...'
This creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default.
When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. This way, when you change a single source file, you can recompile only this file without having to compile the entire project.
To compile an object file on the command line, run the following command:
scl enable devtoolset-2 'gfortran -o object_file -c source_file'
This creates an object file named object_file. If the -o option is omitted, the compiler creates a file named after the source file with the .o file extension. To link object files together and create a binary file, run:
scl enable devtoolset-2 'gfortran -o output_file object_file...'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset gfortran as default:
scl enable devtoolset-2 'bash'
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Chapter 3. GNU Compiler Collection (GCC)
Note
To verify the version of gfortran you are using at any point, type the following at a shell prompt:
which gfortran
Red Hat Developer Toolset's gfortran executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset gfortran:
gfortran -v
Important
Some newer library features are statically linked into applications built with Red Hat Developer
Toolset to support execution on multiple versions of Red Hat Enterprise Linux. This adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons.
Example 3.5. Compiling a Fortran Program on the Command Line
Consider a source file named hello.f with the following contents: program hello print * , "Hello, World!" end program hello
To compile this source code on the command line by using the gfortran compiler from Red Hat
Developer Toolset, type:
~]$ scl enable devtoolset-2 'gfortran -o hello hello.f'
This creates a new binary file called hello in the current working directory.
3.3.3. Running a Fortran Program
When gfortran compiles a program, it creates an executable binary file. To run this program on the command line, change to the directory with the executable file and type:
./file_name
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Red Hat Developer Toolset 2.x User Guide
Example 3.6. Running a Fortran Program on the Command Line
Assuming that you have successfully compiled the hello binary file as shown in Example 3.5,
prompt:
~]$ ./hello
Hello, World!
3.4. Additional Resources
A detailed description of the GNU Compiler Collections and its features is beyond the scope of this book.
For more information, see the resources listed below.
Installed Documentation
gcc(1) — The manual page for the gcc compiler provides detailed information on its usage; with few exceptions, g++ accepts the same command line options as gcc. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man gcc'
gfortran(1) — The manual page for the gfortran compiler provides detailed information on its usage. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man gfortran'
C++ Standard Library Documentation — Documentation on the C++ standard library can be optionally installed by typing the following at a shell prompt as root:
yum install devtoolset-2-libstdc++-docs
Once installed, HTML documentation is available at /opt/rh/devtoolset-
2/root/usr/share/doc/devtoolset-2-libstdc++-docs-4 .8.1/htm l/index.htm l.
Online Documentation
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides in-depth information about GCC.
Using the GNU Compiler Collection — The official GCC manual provides an in-depth description of the GNU compilers and their usage.
The GNU C++ Library — The GNU C++ library documentation provides detailed information about the GNU implementation of the standard C++ library.
The GNU Fortran Compiler — The GNU Fortran compiler documentation provides detailed information on gfortran's usage.
See Also
provides a comprehensive list of features and improvements over the
Red Hat Enterprise Linux system version of the GNU Compiler Collection and the version distributed
36
Chapter 3. GNU Compiler Collection (GCC) in the previous release of Red Hat Developer Toolset, as well as information about the language,
ABI, and debugging compatibility.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides a general introduction to the Eclipse development environment, and describes how to use it with the tools from Red Hat Developer Toolset.
explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries.
explains how to use elfutils, a collection of binary tools to inspect and manipulate
ELF files.
explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size.
provides information on how to debug programs written in C, C++, and Fortran.
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Red Hat Developer Toolset 2.x User Guide
Chapter 4. binutils
binutils is a collection of various binary tools such as the GNU linker, GNU assembler, and other
Red Hat Developer Toolset version of binutils.
Red Hat Developer Toolset is distributed with binutils 2.23.52. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements, including the new gold linker, several new command line options, improvements to the linker script language, and support for link-time optimization, compressed debug sections, and new instruction sets.
For a detailed list of changes, see Section A.3, “Changes in binutils”
.
Table 4 .1. Tools Included in binutils for Red Hat Developer Toolset
Name addr2line ar as c++filt dwp elfedit gprof ld ld.bfd
ld.gold
nm objcopy objdum p ranlib readelf size strings strip
Description
Translates addresses into file names and line numbers.
Creates, modifies, and extracts files from archives.
The GNU assembler.
Decodes mangled C++ symbols.
Combines DWARF object files into a single DWARF package file.
Examines and edits ELF files.
Display profiling information.
The GNU linker.
An alternative to the GNU linker.
A new ELF linker.
Lists symbols from object files.
Copies and translates object files.
Displays information from object files.
Generates an index to the contents of an archive to make access to this archive faster.
Displays information about ELF files.
Lists section sizes of object or archive files.
Displays printable character sequences in files.
Discards all symbols from object files.
4.1. Installing binutils
In Red Hat Developer Toolset, binutils are provided by the devtoolset-2-binutils package and are
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
4.2. Using the GNU Assembler
To produce an object file from an assembly language program, run the as tool as follows:
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Chapter 4. binutils
scl enable devtoolset-2 'as [option...] -o object_file source_file'
This creates an object file named object_file in the current working directory.
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset as as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of as you are using at any point, type the following at a shell prompt:
which as
Red Hat Developer Toolset's as executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset as:
as -v
4.3. Using the GNU Linker
To create an executable binary file or a library from object files, run the ld tool as follows:
scl enable devtoolset-2 'ld [option...] -o output_file object_file...'
This creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default.
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset ld as default:
scl enable devtoolset-2 'bash'
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Red Hat Developer Toolset 2.x User Guide
Note
To verify the version of ld you are using at any point, type the following at a shell prompt:
which ld
Red Hat Developer Toolset's ld executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset ld:
ld -v
4.4. Using Other Binary Tools
The binutils provide many binary tools other than a linker and assembler. For a complete list of these
tools, see Table 4.1, “Tools Included in binutils for Red Hat Developer Toolset”
.
To execute any of the tools that are part of binutils, run the command as follows:
scl enable devtoolset-2 'tool [option...] file_name'
See Table 4.1, “Tools Included in binutils for Red Hat Developer Toolset”
for a list of tools that are distributed with binutils. For example, to use the objdump tool to inspect an object file, type:
scl enable devtoolset-2 'objdump [option...] object_file'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset binary tools as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of binutils you are using at any point, type the following at a shell prompt:
which objdump
Red Hat Developer Toolset's objdump executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset objdump:
objdump -v
4.5. Additional Resources
4 0
Chapter 4. binutils
A detailed description of binutils is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
as(1), ld(1), addr2line(1), ar(1), c++filt(1), dwp(1), elfedit(1), gprof(1), nm(1), objcopy(1),
objdump(1), ranlib(1), readelf(1), size(1), strings(1), strip(1), — Manual pages for various binutils tools provide more information about their respective usage. To display a manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man tool'
Online Documentation
Documentation for binutils — The binutils documentation provides an in-depth description of the binary tools and their usage.
See Also
Section A.3, “Changes in binutils”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of binutils and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
explains how to use elfutils, a collection of binary tools to inspect and manipulate
ELF files.
Chapter 3, GNU Compiler Collection (GCC)
provides information on how to compile programs written in C, C++, and Fortran.
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Chapter 5. elfutils
elfutils is a collection of various binary tools such as eu-objdump, eu-readelf, and other utilities
Toolset version of elfutils.
Red Hat Developer Toolset is distributed with elfutils 0.155. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements.
Table 5.1. Tools Included in elfutils for Red Hat Developer Toolset
Name eu-addr2line eu-ar eu-elfcm p eu-elflint eu-findtextrel eu-m ake-debugarchive eu-nm eu-objdum p eu-ranlib eu-readelf eu-size eu-strings eu-strip eu-unstrip
Description
Translates addresses into file names and line numbers.
Creates, modifies, and extracts files from archives.
Compares relevant parts of two ELF files for equality.
Verifies that ELF files are compliant with the generic ABI (gABI) and
processor-specific supplement ABI (psABI) specification.
Locates the source of text relocations in files.
Creates an offline archive for debugging.
Lists symbols from object files.
Displays information from object files.
Generates an index to the contents of an archive to make access to this archive faster.
Displays information about ELF files.
Lists section sizes of object or archive files.
Displays printable character sequences in files.
Discards all symbols from object files.
Combines stripped files with separate symbols and debug information.
5.1. Installing elfutils
In Red Hat Developer Toolset, elfutils is provided by the devtoolset-2-elfutils package and is
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
5.2. Using elfutils
To execute any of the tools that are part of elfutils, run the command as follows:
scl enable devtoolset-2 'tool [option...] file_name'
See Table 5.1, “Tools Included in elfutils for Red Hat Developer Toolset”
for a list of tools that are distributed with elfutils. For example, to use the eu-objdump tool to inspect an object file, type:
scl enable devtoolset-2 'eu-objdump [option...] object_file'
4 2
Chapter 5. elfutils
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset binary tools as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of elfutils you are using at any point, type the following at a shell prompt:
which eu-objdump
Red Hat Developer Toolset's eu-objdump executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset eu-objdump:
eu-objdump -V
5.3. Additional Resources
A detailed description of elfutils is beyond the scope of this book. For more information, see the resources listed below.
See Also
Section A.4, “Changes in elfutils”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of elfutils and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
Chapter 3, GNU Compiler Collection (GCC)
provides information on how to compile programs written in C, C++, and Fortran.
explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries.
explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size.
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Red Hat Developer Toolset 2.x User Guide
Chapter 6. dwz
dwz is a command line tool that attempts to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size. To do so, dwz replaces DWARF information representation with equivalent smaller representation where possible, and reduces the amount of duplication by using techniques from Appendix E of the DWARF Standard.
Red Hat Developer Toolset is distributed with dwz 0.11.
6.1. Installing dwz
In Red Hat Developer Toolset, the dwz utility is provided by the devtoolset-2-dwz package and is
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
6.2. Using dwz
To optimize DWARF debugging information in a binary file, run the dwz tool as follows:
scl enable devtoolset-2 'dwz [option...] file_name'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset dwz as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of dwz you are using at any point, type the following at a shell prompt:
which dwz
Red Hat Developer Toolset's dwz executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset dwz:
dwz -v
6.3. Additional Resources
A detailed description of dwz and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
dwz(1) — The manual page for the dwz utility provides detailed information on its usage. To display the manual page for the version included in Red Hat Developer Toolset, type:
4 4
Chapter 6. dwz
scl enable devtoolset-2 'man dwz'
See Also
provides a comprehensive list of features and enhancements over the version of dwz distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
Chapter 3, GNU Compiler Collection (GCC)
provides information on how to compile programs written in C, C++, and Fortran.
explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries.
explains how to use elfutils, a collection of binary tools to inspect and manipulate
ELF files.
4 5
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Red Hat Developer Toolset 2.x User Guide
Part IV. Debugging Tools
Chapter 7. GNU Debugger (GDB)
Chapter 7. GNU Debugger (GDB)
The GNU Debugger, commonly abbreviated as GDB, is a command line tool that can be used to debug programs written in various programming languages. It allows you to inspect memory within the code being debugged, control the execution state of the code, detect the execution of particular sections of code, and much more.
Red Hat Developer Toolset is distributed with GDB 7.6. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements, including improved support for Python scripting, ambiguous line specifications, and tracepoints, as well as improved inferior control commands and handling of C++ debugee executables. For a detailed list of
changes, see Section A.6, “Changes in GDB”
.
7.1. Installing the GNU Debugger
In Red Hat Developer Toolset, the GNU Debugger is provided by the devtoolset-2-gdb package and is
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
7.2. Preparing a Program for Debugging
Compiling Programs with Debugging Information
To compile a C program with debugging information that can be read by the GNU Debugger, make sure the gcc compiler is run with the -g option. To do so on the command line, use a command in the following form:
scl enable devtoolset-2 'gcc -g -o output_file input_file...'
Similarly, to compile a C++ program with debugging information, run:
scl enable devtoolset-2 'g++ -g -o output_file input_file...'
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Red Hat Developer Toolset 2.x User Guide
Example 7.1. Compiling a C Program With Debugging Information
Consider a source file named fibonacci.c that has the following contents:
#include <stdio.h>
#include <limits.h> int main ( int argc, char *argv[]) { unsigned long int a = 0; unsigned long int b = 1 ; unsigned long int sum; while (b < LONG_MAX) {
printf( "%ld " , b);
sum = a + b;
a = b;
b = sum;
} return 0;
}
To compile this program on the command line using GCC from Red Hat Developer Toolset with debugging information for the GNU Debugger, type:
~]$ scl enable devtoolset-2 'gcc -g -o fibonacci fibonacci.c'
This creates a new binary file called fibonacci in the current working directory.
Installing Debugging Information for Existing Packages
To install debugging information for a package that is already installed on the system, type the following at a shell prompt as root:
debuginfo-install package_name
Note that the yum-utils package must be installed for the debuginfo-install utility to be available on your system.
Example 7.2. Installing Debugging Information for the glibc Package
To install debugging information for the glibc package, type:
~]# debuginfo-install glibc
Loaded plugins: product-id, refresh-packagekit, subscription-manager
--> Running transaction check
---> Package glibc-debuginfo.x86_64 0:2.12-1.47.el6_2.5 will be installed
...
7.3. Running the GNU Debugger
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Chapter 7. GNU Debugger (GDB)
To run the GNU Debugger on a program you want to debug, type the following at a shell prompt:
scl enable devtoolset-2 'gdb file_name'
This starts the gdb debugger in interactive mode and displays the default prompt, (gdb). To quit the debugging session and return to the shell prompt, run the following command at any time:
quit
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset gdb as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of gdb you are using at any point, type the following at a shell prompt:
which gdb
Red Hat Developer Toolset's gdb executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer
Toolset gdb:
gdb -v
Example 7.3. Running the gdb Utility on the fibonacci Binary File
Assuming that you have successfully compiled the fibonacci binary file as shown in Example 7.1,
“Compiling a C Program With Debugging Information” , you can start debugging it with gdb by typing
the following at a shell prompt:
~]$ scl enable devtoolset-2 'gdb fibonacci'
GNU gdb (GDB) Red Hat Enterprise Linux (7.4.50.20120120-43.el6)
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
(gdb)
7.4. Listing Source Code
To view the source code of the program you are debugging, run the following command:
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Red Hat Developer Toolset 2.x User Guide
list
Before you start the execution of the program you are debugging, gdb displays first ten lines of the source code and any subsequent use of this command lists another ten lines. Once you start the execution, gdb displays the lines that are surrounding the line on which the execution stops, typically when you set a breakpoint.
You can also display the code that is surrounding a particular line. To do so, run the command in the following form:
list [file_name:]line_number
Similarly, to display the code that is surrounding the beginning of a particular function, run:
list [file_name:]function_name
Note that you can change the number of lines the list command displays by running the following command:
set listsize number
Example 7.4 . Listing the Source Code of the fibonacci Binary File
The fibonacci.c file listed in Example 7.1, “Compiling a C Program With Debugging Information”
has exactly 17 lines. Assuming that you have compiled it with debugging information and you want the
gdb utility to be capable of listing the entire source code, you can run the following command to change the number of listed lines to 20:
(gdb) set listsize 20
You can now display the entire source code of the file you are debugging by running the list command with no additional arguments:
(gdb) list
1 #include <stdio.h>
2 #include <limits.h>
3
4 int main (int argc, char *argv[]) {
5 unsigned long int a = 0;
6 unsigned long int b = 1;
7 unsigned long int sum;
8
9 while (b < LONG_MAX) {
10 printf("%ld ", b);
11 sum = a + b;
12 a = b;
13 b = sum;
14 }
15
16 return 0;
17 }
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Chapter 7. GNU Debugger (GDB)
7.5. Setting Breakpoints
Setting a New Breakpoint
To set a new breakpoint at a certain line, run the following command:
break [file_name:]line_number
You can also set a breakpoint on a certain function:
break [file_name:]function_name
Example 7.5. Setting a New Breakpoint
Assuming that you have compiled the fibonacci.c file listed in Example 7.1, “Compiling a C
Program With Debugging Information” with debugging information, you can set a new breakpoint at
line 10 by running the following command:
(gdb) break 10
Breakpoint 1 at 0x4004e5: file fibonacci.c, line 10.
Listing Breakpoints
To display a list of currently set breakpoints, run the following command:
info breakpoints
Example 7.6. Listing Breakpoints
Assuming that you have followed the instructions in Example 7.5, “Setting a New Breakpoint”
, you can display the list of currently set breakpoints by running the following command:
(gdb) info breakpoints
Num Type Disp Enb Address What
1 breakpoint keep y 0x00000000004004e5 in main at fibonacci.c:10
Deleting Existing Breakpoints
To delete a breakpoint that is set at a certain line, run the following command:
clear line_number
Similarly, to delete a breakpoint that is set on a certain function, run:
clear function_name
You can also delete all breakpoints at once. To do so, run the clear command with no additional arguments:
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Red Hat Developer Toolset 2.x User Guide
clear
Example 7.7. Deleting an Existing Breakpoint
Assuming that you have compiled the fibonacci.c file listed in Example 7.1, “Compiling a C
Program With Debugging Information” with debugging information, you can set a new breakpoint at
line 7 by running the following command:
(gdb) break 7
Breakpoint 2 at 0x4004e3: file fibonacci.c, line 7.
To remove this breakpoint, type:
(gdb) clear 7
Deleted breakpoint 2
7.6. Starting Execution
To start execution of the program you are debugging, run the following command:
run
If the program accepts any command line arguments, you can provide them as arguments to the run command:
run argument…
The execution stops when a first breakpoint (if any) is reached, when an error occurs, or when the program terminates.
Example 7.8. Executing the fibonacci Binary File
Assuming that you have followed the instructions in Example 7.5, “Setting a New Breakpoint”
, you can execute the fibonacci binary file by running the following command:
(gdb) run
Starting program: /home/john/fibonacci
Breakpoint 1, main (argc=1, argv=0x7fffffffe4d8) at fibonacci.c:10
10 printf("%ld ", b);
7.7. Displaying Current Values
The gdb utility allows you to display the value of almost anything that is relevant to the program, from a variable of any complexity to a valid expression or even a library function. However, the most common task is to display the value of a variable.
To display the current value of a certain variable, run the following command:
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Chapter 7. GNU Debugger (GDB)
print variable_name
Example 7.9. Displaying the Current Values of Variables
and the execution of the fibonacci binary stopped after reaching the breakpoint at line 10, you can display the current values of variables a and b as follows:
(gdb) print a
$1 = 0
(gdb) print b
$2 = 1
7.8. Continuing Execution
To resume the execution of the program you are debugging after it reached a breakpoint, run the following command:
continue
The execution stops again when another breakpoint is reached. To skip a certain number of breakpoints
(typically when you are debugging a loop), you can run the continue command in the following form:
continue number
The gdb utility also allows you to stop the execution after executing a single line of code. To do so, run:
step
Finally, you can execute a certain number of lines by using the step command in the following form:
step number
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Red Hat Developer Toolset 2.x User Guide
Example 7.10. Continuing the Execution of the fibonacci Binary File
and the execution of the fibonacci binary stopped after reaching the breakpoint at line 10, you can resume the execution by running the following command:
(gdb) continue
Continuing.
Breakpoint 1, main (argc=1, argv=0x7fffffffe4d8) at fibonacci.c:10
10 printf("%ld ", b);
The execution stops the next time the breakpoint is reached. To execute next three lines of code, type:
(gdb) step 3
13 b = sum;
This allows you to verify the current value of the sum variable before it is assigned to b:
(gdb) print sum
$3 = 2
7.9. Additional Resources
A detailed description of the GNU Debugger and all its features is beyond the scope of this book. For more information, see the resources listed below.
Online Documentation
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides more information on the GNU Debugger and debugging.
GDB Documentation — The official GDB documentation includes the GDB User Manual and other reference material.
See Also
provides a comprehensive list of features and improvements over the
Red Hat Enterprise Linux system version of the GNU Debugger and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides a general introduction to the Eclipse development environment, and describes how to use it with the tools from Red Hat Developer Toolset.
Chapter 3, GNU Compiler Collection (GCC)
provides further information on how to compile programs written in C, C++, and Fortran.
documents how to use the strace utility to monitor system calls that a program uses and signals it receives.
documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards.
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Chapter 7. GNU Debugger (GDB)
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Red Hat Developer Toolset 2.x User Guide
Chapter 8. strace
strace is a diagnostic and debugging tool for the command line that can be used to trace system calls that are made and received by a running process. It records the name of each system call, its arguments, and its return value, as well as signals received by the process and other interactions with the kernel, and prints this record to standard error output or a selected file.
Red Hat Developer Toolset is distributed with strace 4 .7.
8.1. Installing strace
In Red Hat Enterprise Linux, the strace utility is provided by the devtoolset-2-strace package and is
automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat
8.2. Using strace
To run the strace utility on a program you want to analyze, type the following at a shell prompt:
scl enable devtoolset-2 'strace program [argument...]'
Replace program with the name of the program you want to analyze, and argument with any command line options and arguments you want to supply to this program. Alternatively, you can run the utility on an already running process by using the -p command line option followed by the process ID:
scl enable devtoolset-2 'strace -p process_id'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset strace as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of strace you are using at any point, type the following at a shell prompt:
which strace
Red Hat Developer Toolset's strace executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset strace:
strace -V
8.2.1. Redirecting Output to a File
By default, strace prints the name of each system call, its arguments and the return value to standard error output. To redirect this output to a file, use the -o command line option followed by the file name:
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Chapter 8. strace
scl enable devtoolset-2 'strace -o file_name program [argument...]'
Replace file_name with the name of the file.
Example 8.1. Redirecting Output to a File
Consider a slightly modified version of the fibonacci file from Example 7.1, “Compiling a C Program
With Debugging Information” . This executable file displays the Fibonacci sequence and optionally
allows you to specify how many members of this sequence to list. To run the strace utility on this file and redirect the trace output to fibonacci.log, type:
~]$ scl enable devtoolset-2 'strace -o fibonacci.log ./fibonacci 20'
1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765
This creates a new plain-text file called fibonacci.log in the current working directory.
8.2.2. Tracing Selected System Calls
To trace only a selected set of system calls, run the strace utility with the -e command line option:
scl enable devtoolset-2 'strace -e expression program [argument...]'
Replace expression with a comma-separated list of system calls to trace or any of the keywords listed
in Table 8.1, “Commonly Used Values of the -e Option”
. For a detailed description of all available values, see the strace(1) manual page.
Table 8.1. Commonly Used Values of the -e Option
Value file process network signal ipc desc
Description
System calls that accept a file name as an argument.
System calls that are related to process management.
System calls that are related to networking.
System calls that are related to signal management.
System calls that are related to inter-process communication (IPC).
System calls that are related to file descriptors.
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Red Hat Developer Toolset 2.x User Guide
Example 8.2. Tracing Selected System Calls
Consider the employee file from Example 9.1, “Using memstomp”
. To run the strace utility on this executable file and trace only the mmap and munmap system calls, type:
~]$ scl enable devtoolset-2 'strace -e mmap,munmap ./employee' mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f896c744000 mmap(NULL, 61239, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f896c735000 mmap(0x3146a00000, 3745960, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3,
0) = 0x3146a00000 mmap(0x3146d89000, 20480, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x189000) = 0x3146d89000 mmap(0x3146d8e000, 18600, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x3146d8e000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f896c734000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f896c733000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f896c732000 munmap(0x7f896c735000, 61239) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f896c743000
John,[email protected],
+++ exited with 0 +++
8.2.3. Displaying Time Stamps
To prefix each line of the trace with the exact time of the day in hours, minutes, and seconds, run the
strace utility with the -t command line option:
scl enable devtoolset-2 'strace -t program [argument...]'
To also display milliseconds, supply the -t option twice:
scl enable devtoolset-2 'strace -tt program [argument...]'
To prefix each line of the trace with the time required to execute the respective system call, use the -r command line option:
scl enable devtoolset-2 'strace -r program [argument...]'
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Chapter 8. strace
Example 8.3. Displaying Time Stamps
Consider an executable file named pwd. To run the strace utility on this file and include time stamps in the output, type:
~]$ scl enable devtoolset-2 'strace -tt ./pwd'
19:43:28.011815 execve("./pwd", ["./pwd"], [/* 36 vars */]) = 0
19:43:28.012128 brk(0) = 0xcd3000
19:43:28.012174 mmap(NULL, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc869cb0000
19:43:28.012427 open("/etc/ld.so.cache", O_RDONLY) = 3
19:43:28.012446 fstat(3, {st_mode=S_IFREG|0644, st_size=61239, ...}) = 0
19:43:28.012464 mmap(NULL, 61239, PROT_READ, MAP_PRIVATE, 3, 0) =
0x7fc869ca1000
19:43:28.012483 close(3) = 0
...
19:43:28.013410 +++ exited with 0 +++
8.2.4. Displaying a Summary
To display a summary of how much time was required to execute each system call, how many times were these system calls executed, and how many errors were encountered during their execution, run the strace utility with the -c command line option:
scl enable devtoolset-2 'strace -c program [argument...]'
Example 8.4 . Displaying a Summary
Consider an executable file named lsblk. To run the strace utility on this file and display a trace summary, type:
~]$ scl enable devtoolset-2 'strace -c ./lsblk > /dev/null'
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
80.88 0.000055 1 106 16 open
19.12 0.000013 0 140 munmap
0.00 0.000000 0 148 read
0.00 0.000000 0 1 write
0.00 0.000000 0 258 close
0.00 0.000000 0 37 2 stat
...
------ ----------- ----------- --------- --------- ----------------
100.00 0.000068 1790 35 total
8.3. Additional Resources
A detailed description of strace and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
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Red Hat Developer Toolset 2.x User Guide
strace(1) — The manual page for the strace utility provides detailed information about its usage.
To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man strace'
See Also
Section A.7, “Changes in strace”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of strace.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides information on how to debug programs written in C, C++, and Fortran.
documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards.
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Chapter 9. memstomp
Chapter 9. memstomp
memstomp is a command line tool that can be used to identify function calls with overlapping memory regions in situations when such an overlap is not permitted by various standards. It intercepts calls to
the library functions listed in Table 9.1, “Function Calls Inspected by memstomp”
and for each memory overlap, it displays a detailed backtrace to help you debug the problem.
Similarly to Valgrind, the memstomp utility inspects applications without the need to recompile them.
However, it is much faster than this tool and therefore serves as a convenient alternative to it.
Red Hat Developer Toolset is distributed with memstomp 0.1.4 .
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Table 9.1. Function Calls Inspected by memstomp
Function m em cpy m em ccpy m em pcpy strcpy stpcpy strncpy stpncpy strcat strncat wm em cpy wm em pcpy wcscpy wcsncpy wcscat wcsncat
Description
Copies n bytes from one memory area to another and returns a pointer to the second memory area.
Copies a maximum of n bytes from one memory area to another and stops when a certain character is found. It either returns a pointer to the byte following the last written byte, or NULL if the given character is not found.
Copies n bytes from one memory area to another and returns a pointer to the byte following the last written byte.
Copies a string from one memory area to another and returns a pointer to the second string.
Copies a string from one memory area to another and returns a pointer to the terminating null byte of the second string.
Copies a maximum of n characters from one string to another and returns a pointer to the second string.
Copies a maximum of n characters from one string to another. It either returns a pointer to the terminating null byte of the second string, or if the string is not null-terminated, a pointer to the byte following the last written byte.
Appends one string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string.
Appends a maximum of n characters from one string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string.
The wide-character equivalent of the memcpy() function that copies n wide characters from one array to another and returns a pointer to the second array.
The wide-character equivalent of the mempcpy() function that copies n wide characters from one array to another and returns a pointer to the byte following the last written wide character.
The wide-character equivalent of the strcpy() function that copies a widecharacter string from one array to another and returns a pointer to the second array.
The wide-character equivalent of the strncpy() function that copies a maximum of n wide characters from one array to another and returns a pointer to the second string.
The wide-character equivalent of the strcat() function that appends one wide-character string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string.
The wide-character equivalent of the strncat() function that appends a maximum of n wide characters from one array to another while overwriting the terminating null byte of the second wide-character string and adding a new one at its end. It returns a pointer to the new string.
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Chapter 9. memstomp
9.1. Installing memstomp
In Red Hat Developer Toolset, the memstomp utility is provided by the devtoolset-2-memstomp package
9.2. Using memstomp
To run the memstomp utility on a program you want to analyze, type the following at a shell prompt:
scl enable devtoolset-2 'memstomp program [argument...]'
To immediately terminate the analyzed program when a problem is detected, run the utility with the --
kill (or -k for short) command line option:
scl enable devtoolset-2 'memstomp --kill program [argument...]'
The use of the --kill option is especially recommended if you are analyzing a multi-threaded program; the internal implementation of backtraces is not thread-safe and running the memstomp utility on a multithreaded program without this command line option can therefore produce unreliable results.
Additionally, if you have compiled the analyzed program with the debugging information or this debugging information is available to you, you can use the --debug-info (or -d) command line option to produce a more detailed backtrace:
scl enable devtoolset-2 'memstomp --debug-info program [argument...]'
For detailed instructions on how to compile your program with the debugging information built in the binary file, see
Section 7.2, “Preparing a Program for Debugging”
. For information on how to install
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset memstomp as default:
scl enable devtoolset-2 'bash'
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Red Hat Developer Toolset 2.x User Guide
Example 9.1. Using memstomp
In the current working directory, create a source file named employee.c with the following contents:
#include <stdio.h>
#include <string.h>
#define BUFSIZE 80 int main( int argc, char *argv[]) { char employee[BUFSIZE] = "John,Doe,[email protected]" ; char name[BUFSIZE] = {0}; char surname[BUFSIZE] = {0}; char *email;
size_t length;
/* Extract the information: */
memccpy(name, employee, ',' , BUFSIZE);
length = strlen(name);
memccpy(surname, employee + length, ',' , BUFSIZE);
length += strlen(surname);
email = employee + length;
/* Compose the new entry: */
strcat(employee, surname);
strcpy(employee, name);
strcat(employee, email);
/* Print the result: */
puts(employee); return 0;
}
Compile this program into a binary file named employee by using the following command:
~]$ scl enable devtoolset-2 'gcc -rdynamic -g -o employee employee.c'
To identify erroneous function calls with overlapping memory regions, type:
~]$ scl enable devtoolset-2 'memstomp --debug-info ./employee' memstomp: 0.1.4 successfully initialized for process employee (pid 14887).
strcat(dest=0x7fff13afc265, src=0x7fff13afc269, bytes=21) overlap for employee(14887)
??:0 strcpy()
??:0 strcpy()
??:0 _Exit()
??:0 strcat()
employee.c:26 main()
??:0 __libc_start_main()
??:0 _start()
John,[email protected],
Chapter 9. memstomp
9.3. Additional Resources
A detailed description of memstomp and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
m em stom p(1) — The manual page for the m em stom p utility provides detailed information about its usage. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man memstomp'
See Also
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides information on how to debug programs written in C, C++, and Fortran.
documents how to use the strace utility to monitor system calls that a program uses and signals it receives.
explains how to use valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls.
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Red Hat Developer Toolset 2.x User Guide
Part V. Performance Monitoring Tools
Chapter 10. SystemTap
Chapter 10. SystemTap
SystemTap is a tracing and probing tool that allows users to monitor the activities of the entire system without needing to instrument, recompile, install, and reboot. It is programmable with a custom scripting language, which gives it expressiveness (to trace, filter, and analyze) and reach (to look into the running kernel and applications).
SystemTap can monitor various types of events, such as function calls within the kernel or applications, timers, tracepoints, performance counters, and so on. Some included example scripts produce output similar to netstat, ps, top, and iostat, others include pretty-printed function callgraph traces or tools for working around security bugs.
Red Hat Developer Toolset is distributed with SystemTap 2.1.
Table 10.1. Tools Distributed with SystemTap for Red Hat Developer Toolset
Name stap staprun stapsh stap-prep stap-m erge stap-report
Description
Translates probing instructions into C code, builds a kernel module, and loads it into a running Linux kernel.
Loads, unloads, attaches to, and detaches from kernel modules built with the stap utility.
Serves as a remote shell for SystemTap.
Determines and—if possible—downloads the kernel information packages that are required to run SystemTap.
Merges per-CPU files. This script is automatically executed when the stap utility is executed with the -b command line option.
Gathers important information about the system for the purpose of reporting a bug in SystemTap.
10.1. Installing SystemTap
In Red Hat Developer Toolset, SystemTap is provided by the devtoolset-2-systemtap package and is
automatically installed with devtoolset-2-perftools as described in Section 1.5, “Installing Red Hat
In order to place instrumentation into the Linux kernel, SystemTap may also require installation of additional packages with debugging information. To determine which packages to install, run the stap-
prep utility as follows:
scl enable devtoolset-2 'stap-prep'
Note that if you execute this command as the root user, the utility automatically offers the packages for installation. For more information on how to install these packages on your system, see the Red Hat
Enterprise Linux SystemTap Beginners Guide.
10.2. Using SystemTap
To execute any of the tools that are part of SystemTap, type the following at a shell prompt:
scl enable devtoolset-2 'tool [option...]'
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Red Hat Developer Toolset 2.x User Guide
See Table 10.1, “Tools Distributed with SystemTap for Red Hat Developer Toolset”
for a list of tools that are distributed with SystemTap. For example, to run the stap tool to build an instrumentation module, type:
scl enable devtoolset-2 'stap [option...] argument...'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset SystemTap as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of SystemTap you are using at any point, type the following at a shell prompt:
which stap
Red Hat Developer Toolset's stap executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset SystemTap:
stap -V
10.3. Additional Resources
A detailed description of SystemTap and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
stap(1) — The manual page for the stap command provides detailed information on its usage, as well as references to other related manual pages. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man stap'
staprun(8) — The manual page for the staprun command provides detailed information on its usage. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man staprun'
SystemTap Tapset Reference Manual — HTML documentation on the most common tapset definitions is located at /opt/rh/devtoolset-2/root/usr/share/doc/devtoolset-2-
system tap-client-2.1/index.htm l.
Online Documentation
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Chapter 10. SystemTap
Red Hat Enterprise Linux 6 SystemTap Beginners Guide — The SystemTap Beginners Guide for
Red Hat Enterprise Linux 6 provides an introduction to SystemTap and its usage.
Red Hat Enterprise Linux 5 SystemTap Beginners Guide — The SystemTap Beginners Guide for
Red Hat Enterprise Linux 5 provides an introduction to SystemTap and its usage.
Red Hat Enterprise Linux 6 SystemTap Tapset Reference — The SystemTap Tapset Reference for
Red Hat Enterprise Linux 6 provides further details about SystemTap.
Red Hat Enterprise Linux 5 SystemTap Tapset Reference — The SystemTap Tapset Reference for
Red Hat Enterprise Linux 5 provides further details about SystemTap.
The SystemTap Documentation — The official SystemTap documentation provides further documentation on SystemTap, as well as numerous examples of SystemTap scripts.
See Also
Section A.8, “Changes in SystemTap”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of SystemTap and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls.
explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why.
documents how to use the Dyninst library to instrument a user-space executable.
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Red Hat Developer Toolset 2.x User Guide
Chapter 11. Valgrind
Valgrind is an instrumentation framework that ships with a number of tools to profile applications. It can be used to detect various memory errors and memory management problems, such as the use of uninitialized memory or improper allocation and freeing of memory, or to identify the use of improper arguments in system calls. For a complete list of profiling tools that are distributed with the Red Hat
Developer Toolset version of Valgrind, see Table 11.1, “Tools Distributed with Valgrind for Red Hat
Valgrind profiles an application by rewriting it and instrumenting the rewritten binary. This allows you to profile your application without the need to recompile it, but it also makes Valgrind significantly slower than other profilers, especially when performing extremely detailed runs. It is therefore not suited to debugging time-specific issues, or kernel-space debugging.
Red Hat Developer Toolset is distributed with Valgrind 3.8.1. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements.
Table 11.1. Tools Distributed with Valgrind for Red Hat Developer Toolset
Name
Memcheck
Cachegrind
Callgrind
Helgrind
DRD
Massif
Description
Detects memory management problems by intercepting system calls and checking all read and write operations.
Identifies the sources of cache misses by simulating the level 1 instruction cache (I1), level 1 data cache (D1), and unified level 2 cache (L2).
Generates a call graph representing the function call history.
Detects synchronization errors in multithreaded C, C++, and Fortran programs that use POSIX threading primitives.
Detects errors in multithreaded C and C++ programs that use POSIX threading primitives or any other threading concepts that are built on top of these POSIX threading primitives.
Monitors heap and stack usage.
11.1. Installing Valgrind
In Red Hat Developer Toolset, Valgrind is provided by the devtoolset-2-valgrind package and is automatically installed with devtoolset-2-perftools. If you intend to use Valgrind to profile parallel programs that use the Message Passing Interface (MPI) protocol, also install the devtoolset-2-valgrind-
openmpi package by typing the following at a shell prompt as root:
yum install devtoolset-2-valgrind-openmpi
For detailed instructions on how to install Red Hat Developer Toolset and related packages to your
system, see Section 1.5, “Installing Red Hat Developer Toolset”
.
11.2. Using Valgrind
To run any of the Valgrind tools on a program you want to profile, type the following at a shell prompt:
scl enable devtoolset-2 'valgrind [--tool=tool] program [argument...]'
See Table 11.1, “Tools Distributed with Valgrind for Red Hat Developer Toolset”
for a list of tools that
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Chapter 11. Valgrind
See Table 11.1, “Tools Distributed with Valgrind for Red Hat Developer Toolset” for a list of tools that are distributed with Valgrind. The argument of the --tool command line option must be specified in lower case, and if this option is omitted, Valgrind uses Memcheck by default. For example, to run
Cachegrind on a program to identify the sources of cache misses, type:
scl enable devtoolset-2 'valgrind --tool=cachegrind program [argument...]'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset Valgrind as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of Valgrind you are using at any point, type the following at a shell prompt:
which valgrind
Red Hat Developer Toolset's valgrind executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset Valgrind:
valgrind --version
11.3. Additional Resources
A detailed description of Valgrind and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
valgrind(1) — The manual page for the valgrind utility provides detailed information on how to use Valgrind. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man valgrind'
Valgrind Documentation — HTML documentation for Valgrind is located at /opt/rh/devtoolset-
2/root/usr/share/doc/devtoolset-2-valgrind-3.8.1/htm l/index.htm l.
Online Documentation
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides more information about Valgrind and its Eclipse plug-in.
Red Hat Enterprise Linux 6 Performance Tuning Guide — The Performance Tuning Guide for Red
Hat Enterprise Linux 6 provides more detailed information about using Valgrind to profile applications.
See Also
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Red Hat Developer Toolset 2.x User Guide
Section A.10, “Changes in Valgrind”
provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of Valgrind and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards.
provides an introduction to SystemTap and explains how to use it to monitor the activities of a running system.
explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why.
documents how to use the Dyninst library to instrument a user-space executable.
Chapter 12. OProfile
Chapter 12. OProfile
OProfile is a low overhead, system-wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system, such as when memory is referenced, the number of level 2 cache (L2) requests, and the number of hardware interrupts received. It consists of a configuration utility, a daemon for collecting data, and a number of tools that can be used to transform the data into a human-readable form. For a complete list of tools that are
OProfile profiles an application without adding any instrumentation by recording the details of every nth event. This allows it to consume fewer resources than Valgrind, but also causes its samples to be less precise. Unlike Valgrind, which only collects data for a single process and its children in user-space,
OProfile is well suited to collect system-wide data on both user-space and kernel-space processes, and requires root privileges to run.
Red Hat Developer Toolset is distributed with OProfile 0.9.8. This version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements.
Table 12.1. Tools Distributed with OProfile for Red Hat Developer Toolset
Name oprofiled opcontrol opannotate oparchive opgprof ophelp opim port opjitconv opreport
Description
The OProfile daemon that collects profiling data.
Starts, stops, and configures the OProfile daemon.
Generates an annotated source file or assembly listing form the profiling data.
Generates a directory containing executable, debug, and sample files.
Generates a summary of a profiling session in a format compatible with
gprof.
Displays a list of available events.
Converts a sample database file from a foreign binary format to the native format.
Converts a just-in-time (JIT) dump file to the Executable and Linkable
Format (ELF).
Generates image and symbol summaries of a profiling session.
12.1. Installing OProfile
In Red Hat Developer Toolset, OProfile is provided by the devtoolset-2-oprofile package and is
automatically installed with devtoolset-2-perftools as described in Section 1.5, “Installing Red Hat
12.2. Using OProfile
To run any of the tools that are distributed with OProfile, type the following at a shell prompt as root:
scl enable devtoolset-2 'tool [option...]'
See Table 12.1, “Tools Distributed with OProfile for Red Hat Developer Toolset”
for a list of tools that are distributed with Valgrind. For example, to use the ophelp command to list available events in the
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Red Hat Developer Toolset 2.x User Guide are distributed with Valgrind. For example, to use the ophelp command to list available events in the
XML format, type:
scl enable devtoolset-2 'ophelp -X'
Note that you can execute any command using the scl utility, causing it to be run with the Red Hat
Developer Toolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. This allows you to run a shell session with Red Hat Developer Toolset OProfile as default:
scl enable devtoolset-2 'bash'
Note
To verify the version of OProfile you are using at any point, type the following at a shell prompt:
which opcontrol
Red Hat Developer Toolset's opcontrol executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat
Developer Toolset OProfile:
opcontrol --version
12.3. Additional Resources
A detailed description of OProfile and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
oprofile(1) — The manual page named oprofile provides an overview of OProfile and available tools. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man oprofile'
opannotate(1), oparchive(1), opcontrol(1), opgprof(1), ophelp(1), opimport(1), opreport(1) —
Manual pages for various tools distributed with OProfile provide more information on their respective usage. To display the manual page for the version included in Red Hat Developer Toolset, type:
scl enable devtoolset-2 'man tool'
Online Documentation
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides more information on OProfile.
Red Hat Enterprise Linux 6 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 6 describes in detail how to install, configure, and start using OProfile on this system.
Red Hat Enterprise Linux 5 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 5 describes in detail how to install, configure, and start using OProfile on this system.
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Chapter 12. OProfile
See Also
Section A.9, “Changes in OProfile”
provides a comprehensive list of changes and improvements over the Red Hat Enterprise Linux system version of OProfile and the version distributed in the previous release of Red Hat Developer Toolset.
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides an introduction to SystemTap and explains how to use it to monitor the activities of a running system.
explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls.
documents how to use the Dyninst library to instrument a user-space executable.
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Red Hat Developer Toolset 2.x User Guide
Chapter 13. Dyninst
The Dyninst library provides an application programming interface (API) for instrumenting and working with user-space executables during their execution. It can be used to insert code into a running program, change certain subroutine calls, or even remove them from the program, and serves as a valuable debugging and performance monitoring tool. The Dyninst API is also commonly used along with
SystemTap to allow non-root users to instrument user-space executables.
Red Hat Developer Toolset is distributed with Dyninst 8.0.
13.1. Installing Dyninst
In Red Hat Developer Toolset, the Dyninst library is provided by the devtoolset-2-dyninst package and
provided by the devtoolset-2-toolchain package.
If you intend to write a custom instrumentation for binaries, install the relevant header files by running the following command as root:
yum install devtoolset-2-dyninst-devel
You can also install API documentation for this library by typing the following at a shell prompt as root:
yum install devtoolset-2-dyninst-doc
For a complete list of documents that are included in the devtoolset-2-dyninst-doc package, see
Section 13.3, “Additional Resources”
. For detailed instructions on how to install optional packages to
your system, see Section 1.5, “Installing Red Hat Developer Toolset”
.
13.2. Using Dyninst
13.2.1. Using Dyninst with SystemTap
To use Dyninst along with SystemTap to allow non-root users to instrument user-space executables, run the stap command with the --dyninst (or --runtime=dyninst) command line option. This tells
stap to translate a SystemTap script into C code that uses the Dyninst library, compile this C code into a shared library, and then load the shared library and run the script. Note that when executed like this, the stap command also requires the -c or -x command line option to be specified.
To use the Dyninst runtime to instrument an executable file, type the following at a shell prompt:
scl enable devtoolset-2 'stap --dyninst -c command [option...] argument...'
Similarly, to use the Dyninst runtime to instrument a user's process, type:
scl enable devtoolset-2 'stap --dyninst -x process_id [option...] argument...'
for more information about the Red Hat Developer Toolset version of
SystemTap. For a general introduction to SystemTap and its usage, see the SystemTap Beginners
Guide for Red Hat Enterprise Linux.
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Chapter 13. Dyninst
13.2.2. Using Dyninst as a Stand-alone Application
Before using the Dyninst library as a stand-alone application, set the value of the DYNINSTAPI_RT_LIB environment variable to the path to the runtime library file. If you are running a 64-bit system, you can do so by typing the following at a shell prompt:
export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset-
2/root/usr/lib64/dyninst/libdyninstAPI_RT.so.8.0
If you are running a 32-bit system, type:
export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset-
2/root/usr/lib/dyninst/libdyninstAPI_RT.so.8.0
This sets the DYNINSTAPI_RT_LIB environment variable in the current shell session.
to monitor the execution of a user-space process. For a detailed explanation of how to use Dyninst, see
the resources listed in Section 13.3, “Additional Resources”
.
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Red Hat Developer Toolset 2.x User Guide
Example 13.1. Using Dyninst as a Stand-alone Application
Consider a source file named exercise.C that has the following contents:
#include <stdio.h> void print_iteration( int value) {
printf( "Iteration number %d \n " , value);
} int main( int argc, char **argv) { int i;
printf( "Enter the starting number: " );
scanf( "%d" , &i); for (; i>0; --i)
print_iteration(i); return 0;
}
This program prompts the user to enter a starting number and then counts down to 1, calling the
print_iteration() function for each iteration in order to print the number to standard output. Now consider another source file named count.C with the following contents:
Chapter 13. Dyninst
#include <stdio.h>
#include <fcntl.h>
#include "BPatch.h"
#include "BPatch_process.h"
#include "BPatch_function.h"
#include "BPatch_Vector.h"
#include "BPatch_thread.h"
#include "BPatch_point.h" void usage() {
fprintf(stderr, "Usage: count <process_id> <function> \n " );
}
// Global information for counter
BPatch_variableExpr *counter = NULL; void createCounter(BPatch_process *app, BPatch_image *appImage) { int zero = 0;
counter = app->malloc(*appImage->findType( "int" ));
counter->writeValue(&zero);
} bool interceptfunc(BPatch_process *app,
BPatch_image *appImage, char *funcName) {
BPatch_Vector<BPatch_function *> func;
appImage->findFunction(funcName, func); if (func.size() == 0) {
fprintf(stderr, "Unable to find function to instrument() \n " );
exit ( -1 );
}
BPatch_Vector<BPatch_snippet *> incCount;
BPatch_Vector<BPatch_point *> *points;
points = func[0]->findPoint(BPatch_entry); if ((*points).size() == 0) {
exit ( -1 );
}
BPatch_arithExpr counterPlusOne(BPatch_plus, *counter, BPatch_constExpr( 1 ));
BPatch_arithExpr addCounter(BPatch_assign, *counter, counterPlusOne); return app->insertSnippet(addCounter, *points);
} void printCount(BPatch_thread *thread, BPatch_exitType) { int val = 0;
counter->readValue(&val, sizeof ( int ));
fprintf(stderr, "Function executed %d times.
\n " , val);
}
BPatch bpatch; int main( int argc, char *argv[]) { int pid; if (argc != 3 ) {
usage();
exit( 1 );
}
pid = atoi(argv[ 1 ]);
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BPatch_process *app = bpatch.processAttach(NULL, pid); if (!app) exit ( -1 );
BPatch_image *appImage = app->getImage();
createCounter(app, appImage);
fprintf(stderr, "Finding function %s(): " , argv[ 2 ]);
BPatch_Vector<BPatch_function*> countFuncs;
fprintf(stderr, "OK \n Instrumenting function %s(): " , argv[ 2 ]);
interceptfunc(app, appImage, argv[ 2 ]);
bpatch.registerExitCallback(printCount);
fprintf(stderr, "OK \n Waiting for process %d to exit...
\n " , pid);
app->continueExecution(); while (!app->isTerminated())
bpatch.waitForStatusChange(); return 0;
}
This program accepts a process ID and a function name as command line arguments and then prints the total number of times the function was called during the execution of the process. You can use the following Makefile to build these two files:
DTS = /opt/rh/devtoolset-2/root
CXXFLAGS = -g -I $( DTS ) /usr/include/dyninst
LBITS := $( shell getconf LONG_BIT ) ifeq ( $( LBITS ), 64)
DYNINSTLIBS = $( DTS ) /usr/lib64/dyninst else
DYNINSTLIBS = $( DTS ) /usr/lib/dyninst endif
.PHONY: all all: count exercise count: count.C
g++ $( CXXFLAGS ) count.C -I /usr/include/dyninst -c
g++ $( CXXFLAGS ) count.o -L $( DYNINSTLIBS ) -ldyninstAPI -o count exercise: exercise.C
g++ $( CXXFLAGS ) exercise.C -o exercise
.PHONY: clean clean:
rm -rf *~ *.o count exercise
To compile the two programs on the command line using the g++ compiler from Red Hat Developer
Toolset, run the make utility as follows:
~]$ scl enable devtoolset-2 make g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst count.C -c g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst count.o -L
/opt/rh/devtoolset-2/root/usr/lib64/dyninst -ldyninstAPI -o count g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst exercise.C -o exercise
This creates new binary files called exercise and count in the current working directory.
In one shell session, execute the exercise binary file as follows and wait for it to prompt you to enter the starting number:
Chapter 13. Dyninst
~]$ ./exercise
Enter the starting number:
Do not enter this number. Instead, start another shell session and type the following at its prompt to set the DYNINSTAPI_RT_LIB environment variable and execute the count binary file:
~]$ export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset-
2/root/usr/lib64/dyninst/libdyninstAPI_RT.so.8.0
~]$ ./count `pidof exercise` print_iteration
Finding function print_iteration(): OK
Instrumenting function print_iteration(): OK
Waiting for process 8607 to exit...
Now switch back to the first shell session and enter the starting number as requested by the
exercise program. For example:
Enter the starting number: 5
Iteration number 5
Iteration number 4
Iteration number 3
Iteration number 2
Iteration number 1
When the exercise program terminates, the count program displays the number of times the
print_iteration() function was executed:
Function executed 5 times.
13.3. Additional Resources
A detailed description of Dyninst and its features is beyond the scope of this book. For more information, see the resources listed below.
Installed Documentation
The devtoolset-2-dyninst-doc package installs the following documents in the /opt/rh/devtoolset-
2/root/usr/share/doc/devtoolset-2-dyninst-doc-8.0/ directory:
Dyninst Programmer's Guide — A detailed description of the Dyninst API is stored in the
DyninstAPI.pdf file.
DynC API Programmer's Guide — An introduction to DynC API is stored in the dynC_API.pdf file.
ParseAPI Programmer's Guide — An introduction to the ParseAPI is stored in the ParseAPI.pdf file.
PatchAPI Programmer's Guide — An introduction to PatchAPI is stored in the PatchAPI.pdf file.
ProcControlAPI Programmer's Guide — A detailed description of ProcControlAPI is stored in the
ProcControlAPI.pdf file.
StackwalkerAPI Programmer's Guide — A detailed description of StackwalkerAPI is stored in the
stackwalker.pdf file.
SymtabAPI Programmer's Guide — An introduction to SymtabAPI is stored in the SymtabAPI.pdf file.
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InstructionAPI Reference Manual — A detailed description of the InstructionAPI is stored in the
InstructionAPI.pdf file.
For information on how to install this package on your system, see
Section 13.1, “Installing Dyninst”
.
Online Documentation
Dyninst Home Page — The project home page provides links to additional documentation and related publications.
Red Hat Enterprise Linux 6 SystemTap Beginners Guide — The SystemTap Beginners Guide for
Red Hat Enterprise Linux 6 provides an introduction to SystemTap and its usage.
Red Hat Enterprise Linux 5 SystemTap Beginners Guide — The SystemTap Beginners Guide for
Red Hat Enterprise Linux 5 provides an introduction to SystemTap and its usage.
Red Hat Enterprise Linux 6 SystemTap Tapset Reference — The SystemTap Tapset Reference for
Red Hat Enterprise Linux 6 provides further details about SystemTap.
Red Hat Enterprise Linux 5 SystemTap Tapset Reference — The SystemTap Tapset Reference for
Red Hat Enterprise Linux 5 provides further details about SystemTap.
See Also
Chapter 1, Red Hat Developer Toolset
provides an overview of Red Hat Developer Toolset and more information on how to install it on your system.
provides an introduction to SystemTap and explains how to use it to monitor the activities of a running system.
explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls.
explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why.
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Part VI. Getting Help
Part VI. Getting Help
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Red Hat Developer Toolset 2.x User Guide
Chapter 14. Accessing Red Hat Product Documentation
Red Hat Product Documentation located at https://access.redhat.com/site/documentation/ serves as a central source of information. It is currently translated in 22 languages and for each product, it provides different kinds of books from release and technical notes to installation, user, and reference guides in
HTML, PDF, and EPUB formats.
Below is a brief list of documents that are directly or indirectly relevant to this book.
Red Hat Developer Toolset
Red Hat Developer Toolset 2.0 Release Notes — The Release Notes for Red Hat Developer Toolset
2.0 provide more information about this product.
Red Hat Developer Toolset 2.0 Software Collections Guide — The Software Collections Guide for
Red Hat Developer Toolset 2.0 explains the concept of Software Collections and documents the scl tool.
Red Hat Enterprise Linux
Red Hat Enterprise Linux 6 Developer Guide — The Developer Guide for Red Hat Enterprise Linux 6 provides detailed information about libraries and runtime support, compiling and building, debugging, and profiling.
Red Hat Enterprise Linux 6 Installation Guide — The Installation Guide for Red Hat Enterprise Linux
6 explains how to obtain, install, and update the system.
Red Hat Enterprise Linux 5 Installation Guide — The Installation Guide for Red Hat Enterprise Linux
5 explains how to obtain, install, and update the system.
Red Hat Enterprise Linux 6 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 6 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 6.
Red Hat Enterprise Linux 5 Deployment Guide — The Deployment Guide for Red Hat Enterprise
Linux 5 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 5.
84
Chapter 15. Accessing the Customer Portal
Chapter 15. Accessing the Customer Portal
The Customer Portal is available to all Red Hat subscribers and can be accessed at https://access.redhat.com/home . This web page serves as a pointer to a vast number of resources but of most interest to developers are the Plan, Deploy, and Connect menus. These include links to all the resources needed during each stage of the development.
15.1. The Plan Menu
Figure 15.1. The Plan Menu
In the Plan menu are resources needed to plan a development project. These menu items provide proven resources to implement the best solution the first time. This includes:
Webinars
The Webinars page contains information on upcoming Red Hat and open source events around the world. Here you can register for upcoming webinars or watch archived ones on demand.
Success Stories
Read the success stories of other Red Hat customers to learn how leading organizations are finding unbeatable value, performance, security and reliability with Red Hat solutions.
Product Documentation
This provides a list of links to the various Red Hat documents, including books for Red Hat
Enterprise Linux, Identity Management and Infrastructure, Red Hat Enterprise Storage, JBoss
Enterprise Middleware, and System Management.
Reference Architectures
Reference Architectures contains a list of whitepapers that detail technical case studies of solutions that have been built, tested, and bench-marked by senior Red Hat engineers. They explain the capabilities and limitations of a given solution, as well as detailed notes on how to implement the solution.
Evaluations & Demos
You can download free evaluations of various Red Hat products from here, including Red Hat
Enterprise Linux, Red Hat Enterprise Virtualization, Red Hat Storage Appliance, and JBoss
Enterprise Middleware evaluations.
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Red Hat Developer Toolset 2.x User Guide
Certified Hardware
This section has information on what systems, components, and peripherals Red Hat
Enterprise Linux 6, 5, and 4 support.
15.2. The Deploy Menu
Figure 15.2. The Deploy Menu
In the Deploy menu are resources needed to deploy a development project. This includes:
Getting Started
The Getting Started page has links to information to help get up and running with Red Hat subscriptions, including product registration information, accessing your resources, and engaging in global support. It also has links to a Red Hat Welcome Kit and a Quick Guide to
Red Hat Support.
Downloads
Here is where you can download all that Red Hat offers with descriptions of what each entails.
Activate a New Subscription
After purchasing a Red Hat subscription this is where you go to activate it. Note that the
Activate a New Subscription section requires you to enter your Red Hat login and password.
Support Essentials
Here you can find a list of articles and group discussions, viewable by new posts, most popular, and recent comments, as well as the most recent Red Hat errata.
Security
Red Hat releases errata to address bugs, provide enhancements, or to fix security vulnerabilities. With each erratum an advisory is supplied to give the details of the issues being fixed, as well as how to obtain and install the required software packages. This section has information about the errata, including:
Checking the security update policy and lifetime for all Red Hat products
Getting the latest security updates for Red Hat products
Getting notified of new security updates
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Chapter 15. Accessing the Customer Portal
Finding out if a specific CVE affects a Red Hat product
Reporting a security vulnerability
How we measure security vulnerabilities
Security Response Team mission and standards of service
Support
This is where all the information regarding Red Hat support can be found, including links for:
Support Cases
Support Programs
Product Life Cycles
Supported Environments
Help & Assistance
Site Help
15.3. The Connect Menu
Figure 15.3. The Connect Menu
The Connect menu allows you to connect to the industry's best engineers and collaborate with industry peers. This includes:
Knowledgebase
The Knowledgebase contains a large number of whitepapers on a variety of topics which can serve as another source of documentation for your project. Note that the Knowledgebase section requires you to enter your Red Hat login and password.
Groups
This section allows users to join a group to collaborate on the documents. They can also create and comment on discussions to interact with other customers, Red Hat support staff, and certified engineers. Note that the Groups section requires you to enter your Red Hat login and password.
Videos
A number of videos on how to get vital solutions, useful tips, product demonstrations, and inside information can be accessed from here. You can also rate and comment on all of the videos.
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Tech Briefs
Tech briefs provide practical advice to help solve real-world problems with Red Hat products.
Each tech brief provides a detailed use case covering best practices, how-to instructions, or detailed discussions on how to use Red Hat technology effectively, and are reviewed and tested by Red Hat engineers.
Source
This is the kernel source browser and contains links to all the kernel sources broken into each individual patch, unlike the kernel srpm which is shipped as one big patch. Note that the
Source section requires you to enter your Red Hat login and password.
Support Cases
This is where users can view all their support cases, make changes or view any updates. Note that the Support Cases section requires you to enter your Red Hat login and password.
Chapter 16. Contacting Global Support Services
Chapter 16. Contacting Global Support Services
Unless you have a Self-Support subscription, when both the Red Hat Documentation website and
Customer Portal fail to provide the answers to your questions, you can contact Global Support
Services (GSS).
16.1. Gathering Required Information
Several items of information should be gathered before contacting GSS.
Background Information
Ensure you have the following background information at hand before calling GSS:
Hardware type, make, and model on which the product runs
Software version
Latest upgrades
Any recent changes to the system
An explanation of the problem and the symptoms
Any messages or significant information about the issue
Note
If you ever forget your Red Hat login information, it can be recovered at https://access.redhat.com/site/help/LoginAssistance.html
.
Diagnostics
The diagnostics report for Red Hat Enterprise Linux is required as well. This report is also known as a
sosreport and the program to create the report is provided by the sos package. To install the sos package and all its dependencies on your system, type the following at a shell prompt as root:
yum install sos
To generate the report, run as root:
sosreport
For more information, access the Knowledgebase article at https://access.redhat.com/kb/docs/DOC-
3593 .
Account and Contact Information
In order to help you, GSS requires your account information to customize their support, as well contact information to get back to you. When you contact GSS ensure you have your:
Red Hat customer number or Red Hat Network (RHN) login name
Company name
Contact name
Preferred method of contact (phone or email) and contact information (phone number or email address)
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Red Hat Developer Toolset 2.x User Guide
Issue Severity
Determining an issue's severity is important to allow the GSS team to prioritize their work. There are four levels of severity.
Severity 1 (urgent)
A problem that severely impacts your use of the software for production purposes. It halts your business operations and has no procedural work around.
Severity 2 (high)
A problem where the software is functioning but production is severely reduced. It causes a high impact to business operations and no work around exists.
Severity 3 (medium)
A problem that involves partial, non-critical loss of the use of the software. There is a medium to low impact on your business and business continues to function by utilizing a work around.
Severity 4 (low)
A general usage question, report of a documentation error, or a recommendation for a future product improvement.
For more information on determining the severity level of an issue, see https://access.redhat.com/support/policy/severity .
Once the issue severity has been determined, submit a service request through the Customer Portal under the Connect option, or at https://access.redhat.com/support/contact/technicalSupport.html
. Note that you need your Red Hat login details in order to submit service requests.
If the severity is level 1 or 2, then follow up your service request with a phone call. Contact information and business hours are found at https://access.redhat.com/support/contact/technicalSupport.html
.
If you have a premium subscription, then after hours support is available for Severity 1 and 2 cases.
Turn-around rates for both premium subscriptions and standard subscription can be found at https://access.redhat.com/support/offerings/production/sla.html
.
16.2. Escalating an Issue
If you feel as though an issue is not being handled correctly or adequately, you can escalate it. There are two types of escalation:
Technical escalation
If an issue is not being resolved appropriately or if you need a more senior resource to attend to it.
Management escalation
If the issue has become more severe or you believe it requires a higher priority.
More information on escalation, including contacts, is available at
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Chapter 16. Contacting Global Support Services https://access.redhat.com/support/policy/mgt_escalation.html
.
16.3. Re-opening a Service Request
If more relevant information regarding a closed service request (such as the problem reoccurring), you can re-open it via the Red Hat Customer Portal at https://access.redhat.com/support/policy/mgt_escalation.html
or by calling your local support center, the details of which can be found at https://access.redhat.com/support/contact/technicalSupport.html
.
Important
In order to re-open a service request, you need the original service request number.
16.4. Additional Resources
For more information, see the resources listed below.
Online Documentation
Getting Started — The Getting Started page serves as a starting point for people who purchased a
Red Hat subscription, and offers the Red Hat Welcome Kit and Quick Guide to Red Hat Support for download.
How can a RHEL Self-Support subscription be used?
— A Knowledgebase article for customers with a Self-Support subscription.
Red Hat Global Support Services and public mailing lists — A Knowledgebase article that answers frequent questions about public Red Hat mailing lists.
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Red Hat Developer Toolset 2.x User Guide
Changes in Version 2.0
The sections below document features and compatibility changes introduced in Red Hat Developer
Toolset 2.0.
A.1. Changes in Eclipse
Red Hat Developer Toolset 2.0 is distributed with Eclipse 4 .3 and a wide selection of plug-ins from the
Eclipse Foundation's 2013 Eclipse 4.3 “Kepler” release, and provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features compatibility changes in this release. For details on how to use these new features, see the built-in Eclipse documentation.
A.1.1. Changes Since Red Hat Enterprise Linux 6.4
The following features have been added since the release of the Eclipse Platform and native plug-ins included in Red Hat Enterprise Linux 6.4:
The Eclipse Platform has been updated to from version 3.6 to 4.3. This new major release features a more flexible user interface based on Eclipse Modeling Framework (EMF), CSS-based themes, dependency injection, and more.
The Eclipse C/C++ Development Toolkit (CDT) has been updated from version 7.0 to 8.2. This new major release includes: a greatly enhanced indexer, both in terms of capabilities and speed; improved GNU Debugger integration; support for GNU Debugger's pretty-printing; multi-process debugging; project-less debugging; enhanced refactoring; code-checking capabilities; an improved and more polished user interface.
Mylyn, a set of task and application life cycle management plug-ins, has been updated from version
3.4 to 3.9. This update includes: an enhanced task-focused interface and task editing; a new Jenkins/Hudson connector; enhanced Bugzilla and Trac connectors;
EPUB authoring tools.
A new EGit plug-in has been added. This plug-in includes an Eclipse Team provider based on JGit, a Git implementation written entirely in Java, and adds support for the Git revision control system to the Eclipse user interface by introducing the History and Synchronize views, Compare and
Quick Diff menu items, and various wizards to make it easier for developers to use this plug-in.
New GCov integration has been added to allow the user to visualize GCov output in both summarized form and in file editors. As well, graphing capabilities for the data have been added.
New GProf integration has been added to allow the user to view profiling information such as execution time and call graphs. As well, graphing capabilities for the data have been added.
A new SystemTap integration plug-in has been added. This plug-in includes: an editor for the .stp files with the autocomplete feature; the Probe view with a list of probes that are available on the system; the Function view with a list of functions that are available on the system and can be used in
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Changes in Version 2.0
.stp scripts.
As well, this plug-in includes integration for running SystemTap scripts and viewing the results in a textual, tabular, and graphical manner. Note that the result sets are updated in a near-runtime way, which allows the user to use this plug-in for longer-running monitoring tasks.
New kernel perf tool integration has been added. This plug-in uses the performance counters subsystem of the Linux kernel to profile applications, makes it easier to analyze the results by hyperlinking to the sources in the workspace projects, simplifies the perf tool configuration by selecting the counters to be used, and allows the user to run this tool remotely.
A unified profiling launcher has been added to provide a single method to launch profiling. It allows the user to select a profiling category (Memory, Timing, or Coverage) and back ends for this category (such as OProfile, perf, or GProf for Timing).
The C/C++ documentation plug-in has been enhanced to recognize and use gtk-doc generated documentation and to display it in the Eclipse Help Center.
The OProfile plug-in has been enhanced to support root privilege authentication through polkit.
This feature is configured automatically.
The Valgrind plug-in now supports the Helgrind tool, which can be used to detect synchronization problems such as race conditions, deadlocks caused by incorrect locking order, or misuse of the
POSIX pthreads API. When a problem is detected, the plug-in displays error markers on the corresponding lines in the source code.
A.2. Changes in GCC
Red Hat Developer Toolset 2.0 is distributed with GCC 4 .8, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in
Red Hat Developer Toolset 1.1. Below is a comprehensive list of new features and compatibility changes in this release.
A.2.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of GCC included in Red Hat Developer
Toolset 1.1.
A.2.1.1. Caveats
Aggressive Loop Optimizations
The loop optimizer of GCC has been improved to use language constraints in order to derive bounds for the number of iterations of a loop. The bounds are then used as a guide to loop unrolling, peeling, and loop exit test optimizations.
The optimizations assume that the loop code does not invoke undefined behavior by, for example, causing signed integer overflows or making out-of-bound array accesses. For example, consider the following code fragment: unsigned int foo()
{ unsigned int data_data[ 128 ]; for ( int fd = 0; fd < 128 ; ++fd)
data_data[fd] = fd * (0x02000001); // error return data_data[0];
}
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Red Hat Developer Toolset 2.x User Guide
When the value of the fd variable is 64 or above, the fd * 0x02000001 operation overflows, which is invalid in both C and C++ for signed integers. In the example above, GCC may generate incorrect code or enter an infinite loop.
To fix this error, use the appropriate casts when converting between signed and unsigned types to avoid overflows, for instance: data_data[fd] = (uint32_t) fd * (0x02000001U); // ok
If necessary, this optimization can be turned off by using the new command line option -fno-
aggressive-loop-optim izations.
A.2.1.2. General Improvements and Changes
New Local Register Allocator
GCC 4.8 features a new Local Register Allocator (LRA), which replaces the 26-year old reload pass and improves the quality of generated code. The new local register allocator is meant to be simpler, easier to debug, and does a better job of register allocation.
AddressSanitizer
A fast memory error detector called AddressSanitizer has been added and can be enabled by using the
-fsanitize=address command line option. It augments memory access instructions in order to detect use-after-free and out-of-bound accesses to objects on the heap.
ThreadSanitizer
A fast data race detector called ThreadSanitizer has been added in GCC 4.8. The option to enable this feature is -fsanitize=thread.
Compiling Extremely Large Functions
Many scalability bottlenecks have been removed from GCC optimization passes. As a consequence, it is now possible to compile extremely large functions with smaller memory consumption in less time.
New -Og Optimization Level
A new general optimization level, -Og, has been introduced. This optimization level addresses the need for fast compilation and a superior debugging experience while providing a reasonable level of runtime performance. Overall, the development experience should be better than the default optimization level -
O0.
Caret Diagnostic Messages
The diagnostic messages of GCC, which display a line of source code, now also show a caret that indicates the column where the problem was detected. For example: fred.cc:4:15: fatal error: foo: No such file or directory
#include <foo>
^ compilation terminated.
New -fira-hoist-pressure Option
A new command line option, -fira-hoist-pressure, has been added. This option uses the register allocator to help decide when it is worthwhile to move expressions out of loops. It can reduce the size of
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Changes in Version 2.0 the compiler code, but it slows down the compiler. This option is enabled by default at -Os.
New -fopt-info Option
A new command line option, -fopt-info, has been added. This option controls printing information about the effects of particular optimization passes, and takes the following form:
-fopt-info[-info][=file_name]
The info part of the option controls what is printed. Replace it with optimized to print information when optimization takes place, missed to print information when optimization does not take place, note to print more verbose information, or optall to print everything.
Replace file_name with the name of the file in which you want the information to be written. If you omit this part of the option, GCC writes the information to the standard error output stream.
For example, to display a list of optimizations that were enabled by the -O2 option but had no effect when compiling a file named foo.c, type:
gcc -O2 -fopt-info-missed foo.c
New -floop-nest-optimize Option
A new command line option, -floop-nest-optimize, has been added. This option enables an experimental ISL-based loop nest optimizer, a generic loop nest optimizer that is based on the Pluto optimization algorithms and that calculates a loop structure optimized for data-locality and paralelism.
For more information about this optimizer, see http://pluto-compiler.sourceforge.net
.
Hot and Cold Attributes on Labels
The hot and cold function attributes can now also be applied to labels. Hot labels tell the compiler that the execution path following the label is more likely than any other execution path, and cold labels convey the opposite meaning. These attributes can be used in cases where __builtin_expect cannot be used, for instance with a computed goto or asm goto.
A.2.1.3. Debugging Enhancements
DWARF4
DWARF4 is now used as the default debugging data format when generating debugging information. To get the maximum benefit from this new debugging representation, use the latest version of Valgrind,
elfutils, and GDB included in this release.
New -gsplit-dwarf Option
A new command line option, -gsplit-dwarf, has been added. This option tells the compiler driver to separate as much DWARF debugging information as possible into a separate output file with the .dwo file extension, and allows the build system to avoid linking files with debugging information.
In order to be useful, this option requires a debugger capable of reading .dwo files, such as the version of GDB included in Red Hat Developer Toolset 2.0.
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Note
elfutils, SystemTap, and Valgrind do not support the .dwo files.
A.2.1.4 . C++ Changes
Experimental C++ Features from an Upcoming Standard
g++ now supports a new command line option, -std=c++1y. This option can be used for experimentation with features proposed for the next revision of the standard that is expected around
2014. Currently, the only difference from -std=c++11 is support for return type deduction in normal functions as proposed in N3386 .
New thread_local Keyword
g++ now implements the C++11 thread_local keyword. In comparison with the GNU __thread keyword, thread_local allows dynamic initialization and destruction semantics. See the next item for dynamic initialization issues.
Dynamic Initialization of Thread-local Variables
The C++11 and OpenMP standards allow thread-local and thread-private variables to have dynamic
(that is, runtime) initialization. To support this, any use of such a variable goes through a wrapper function that performs necessary initialization.
When the use and definition of the variable are in the same translation unit, this overhead can be optimized away, but when the use is in a different translation unit, there is significant overhead even if the variable does not actually need dynamic initialization. If the programmer can be sure that no use of the variable in a non-defining translation unit needs to trigger dynamic initialization (either because the variable is statically initialized, or a use of the variable in the defining translation unit will be executed before any uses in another translation unit), they can avoid this overhead by using the new -fno-
extern-tls-init option.
By default, g++ uses the -fextern-tls-init option.
C++11 Attribute Syntax
g++ now implements the C++11 attribute syntax, for example:
[[noreturn]] void f();
C++11 Alignment Specifier
g++ now implements the C++11 alignment specifier, for example: alignas( double ) int i;
A.2.1.5. Fortran Changes
A.2.1.5.1. Caveats
The version of module files (the .mod files) has been incremented. Fortran modules compiled by earlier
GCC versions have to be recompiled when they are used by files compiled with GCC 4.8, as this version of GCC is not able to read .mod files created by earlier versions; attempting to do so fails with an error
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Changes in Version 2.0 message.
Note
The ABI of the produced assembler data itself has not changed; object files and libraries are fully
compatible with older versions except as noted in Section A.2.1.5.2, “ABI Compatibility”
.
A.2.1.5.2. ABI Compatibility
Some internal names used in the assembler or object file have changed for symbols declared in the specification part of a module. If an affected module — or a file using it via use association — is recompiled, the module and all files which directly use such symbols have to be recompiled as well. This change only affects the following kind of module symbols:
Procedure pointers. Note that C-interoperable function pointers (type(c_funptr)) are not affected, nor are procedure-pointer components.
Deferred-length character strings.
A.2.1.5.3. Other Changes
BACKTRACE Intrinsic
A new intrinsic subroutine, BACKTRACE, has been added. This subroutine shows a backtrace at an arbitrary place in user code, program execution continues normally afterwards.
Floating Point Numbers with “q” as Exponential
Reading floating point numbers that use q for the exponential (such as 4.0q0) is now supported as a vendor extension for better compatibility with old data files. It is strongly recommended to use the equivalent but standard conforming e (such as 4.0e0) for I/O.
For Fortran source code, consider replacing the q in floating-point literals by a kind parameter (such as
4 .0e0_qp with a suitable qp). Note that — in Fortran source code — replacing q with a simple e is not equivalent.
GFORTRAN_TMPDIR Environment Variable
The GFORTRAN_TMPDIR environment variable for specifying a non-default directory for files opened with STATUS="SCRATCH", is not used anymore. Instead, gfortran checks the POSIX/GNU standard
T MPDIR environment variable and if T MPDIR is not defined, gfortran falls back to other methods to determine the directory for temporary files as documented in the user manual.
Fortran 2003
Support for unlimited polymorphic variables (CLASS(*)) has been added. Non-constant character lengths are not yet supported.
TS 29113
Assumed types (TYPE(*)) are now supported.
Experimental support for assumed-rank arrays (dimension(..)) has been added. Note that at the moment, the gfortran array descriptor is used, which is different from the array descriptor defined in
TS 29113. For more information, see the header file of gfortran or use the Chasm language interoperability tools.
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A.2.1.6. x86-specific Improvements
New Instructions
GCC 4.8 has added support for the Intel FXSR, XSAVE, and XSAVEOPT instructions. Corresponding intrinsics and built-in functions can now be enabled by using the -mfxsr, -mxsave, and -mxsaveopt command line options respectively.
In addition, support for the RDSEED, ADCX, ADOX, and PREFETCHW instructions has been added and can be enabled by using the -mrdseed, -madx, and -mprfchw command line options.
New Built-in Functions to Detect Run-time CPU Type and ISA
A new built-in function, __builtin_cpu_is(), has been added to detect if the run-time CPU is of a particular type. This function accepts one string literal argument with the CPU name, and returns a positive integer on a match and zero otherwise. For example, __builtin_cpu_is("westmere") returns a positive integer if the run-time CPU is an Intel Core i7 Westmere processor. For a complete list of valid CPU names, see the user manual.
A new built-in function, __builtin_cpu_supports(), has been added to detect if the run-time CPU supports a particular ISA feature. This function accepts one string literal argument with the ISA feature, and returns a positive integer on a match and zero otherwise. For example,
__builtin_cpu_supports("ssse3") returns a positive integer if the run-time CPU supports SSSE3 instructions. For a complete list of valid ISA names, see the user manual.
Important
If these built-in functions are called before any static constructors are invoked, such as IFUNC initialization, then the CPU detection initialization must be explicitly run using this newly provided built-in function, __builtin_cpu_init(). The initialization needs to be done only once. For example, the following is sample invocation inside an IFUNC initializer: static void (*some_ifunc_resolver( void ))( void )
{
__builtin_cpu_init(); if (__builtin_cpu_is( "amdfam10h" ) ...
if (__builtin_cpu_supports( "popcnt" ) ...
}
Function Multiversioning
Function multiversioning allows the programmer to specify multiple versions of the same function, each of which is specialized for a particular variant of a given target. At runtime, the appropriate version is automatically executed depending upon the target where the execution takes place. For example, consider the following code fragment:
__attribute__ ((target ( "default" ))) int foo () { return 0; }
__attribute__ ((target ( "sse4.2" ))) int foo () { return 1 ; }
__attribute__ ((target ( "arch=atom" ))) int foo () { return 2 ; }
When the function foo() is executed, the result returned depends upon the architecture where the program runs, not the architecture where the program was compiled. See the GCC Wiki for more details.
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New RTM and HLE Intrinsics
Support for the Intel RTM and HLE intrinsics, built-in functions, and code generation has been added and can be enabled by using the -mrtm and -mhle command line options. This is done via intrinsics for
Restricted Transactional Memory (RTM) and extensions to the memory model for Hardware Lock Elision
(HLE).
For HLE, two new flags can be used to mark a lock as using hardware elision:
__ATOMIC_HLE_ACQUIRE
Starts lock elision on a lock variable. The memory model in use must be __ATOMIC_ACQUIRE or stronger.
__ATOMIC_HLE_RELEASE
Ends lock elision on a lock variable. The memory model must be __ATOMIC_RELEASE or stronger.
For example, consider the following code fragment: while (__atomic_exchange_n (& lockvar, 1 , __ATOMIC_ACQUIRE
| __ATOMIC_HLE_ACQUIRE))
_mm_pause ();
// work with the acquired lock
__atomic_clear (& lockvar, __ATOMIC_RELEASE | __ATOMIC_HLE_RELEASE);
The new intrinsics that support Restricted Transactional Memory are:
unsigned _xbegin (void)
Attempts to start a transaction. If it succeeds, this function returns _XBEGIN_STARTED, otherwise it returns a status value indicating why the transaction could not be started.
void _xend (void)
Commits the current transaction. When no transaction is active, this function causes a fault. All memory side effects of the transactions become visible to other threads in an atomic manner.
int _xtest (void)
Returns a non-zero value if a transaction is currently active, or zero if it is not.
void _xabort (unsigned char status)
Aborts the current transaction. When no transaction is active, this is a no-op. The parameter
status is included in the return value of any _xbegin() call that is aborted by this function.
The following example illustrates the use of these intrinsics:
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Red Hat Developer Toolset 2.x User Guide if ((status = _xbegin ()) == _XBEGIN_STARTED)
{
// some code
_xend ();
} else
{
// examine the status to see why the transaction failed and possibly retry
}
Transactions Using Transactional Synchronization Extensions
Transactions in the transactional memory feature (the -fgnu-tm option) of GCC can now be run using
Transactional Synchronization Extensions (TSX) if available on x86 hardware.
Support for AMD Family 15h Processors
The x86 backend of GCC now supports CPUs based on AMD Family 15h cores with the 64-bit x86 instruction set support. This can be enabled by using the -march=bdver3 option.
Support for AMD Family 16h Processors
The x86 backend of GCC now supports CPUs based on AMD Family 16h cores with the 64-bit x86 instruction set support. This can be enabled by using the -march=btver2 option.
A.2.2. Changes Since Red Hat Enterprise Linux 6.4 and 5.9
The following features have been added since the release of GCC included in Red Hat Enterprise Linux
6.4 and 5.9:
A.2.2.1. Status and Features
A.2.2.1.1. C++11
GCC 4.7 and later provides experimental support for building applications compliant with C++11 using the -std=c++11 or -std=gnu++11 command line options. However, there is no guarantee for compatibility between C++11 code compiled by different versions of the compiler. Refer to
for details.
The C++ runtime library, libstdc++, supports a majority of the C++11 features. However, there is no or only partial support for some features such as certain properties on type traits or regular expressions. For details, refer to the
libstdc++ documentation
, which also lists implementationdefined behavior.
Support for C++11 exception_ptr and future requires changes to the exception handling runtime in the system libstdc++ package. These changes will be distributed through the normal Z-stream channel.
Application of all Red Hat Enterprise Linux errata may be required to see correct runtime functionality when using these features.
A.2.2.1.2. C11
GCC 4.7 and later provides experimental support for some of the features from the C11 revision of the
ISO C standard, and in addition to the previous (now deprecated) -std=c1x and -std=gnu1x command line options, gcc now accepts -std=c11 and -std=gnu11. Note that since this support is experimental, it may change incompatibly in future releases.
Examples for features that are supported are Unicode strings (including the predefined macros
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Changes in Version 2.0
__ST DC_UT F_16__ and __ST DC_UT F_32__), nonreturning functions (_Noreturn and
<stdnoreturn.h>), and alignment support (_Alignas, _Alignof, max_align_t, and <stdalign.h>).
A.2.2.1.3. Parallelism and Concurrency
GCC 4 .7 and later provides improved support for programming parallel applications:
1. The GCC compilers support the OpenMP API specification for parallel programming, version 3.1.
Refer to the OpenMP website for more information about this specification.
2. The C++11 and C11 standards provide programming abstractions for multi-threaded programs.
The respective standard libraries include programming abstractions for threads and threadrelated features such as locks, condition variables, or futures. These new versions of the standard also define a memory model that precisely specifies the runtime behavior of a multithreaded program, such as the guarantees provided by compilers and the constraints programmers have to pay attention to when writing multi-threaded programs.
Note that support for the memory model is still experimental (see below for details). For more
information about the status of support for C++11 and C11, refer to Section A.2.2.1.1, “C++11”
and
respectively.
The rest of this section describes two new GCC features in more detail. Both these features make it easier for programmers to handle concurrency (such as when multiple threads do not run truly in parallel but instead have to synchronize concurrent access to shared state), and both provide atomicity for access to memory but differ in their scope, applicability, and complexity of runtime support.
C++11 Types and GCC Built-ins for Atomic Memory Access
C++11 has support for atomic types. Access to memory locations of this type is atomic, and appears as one indivisible access even when other threads access the same memory location concurrently. The atomicity is limited to a single read or write access or one of the other atomic operations supported by such types (for example, two subsequent operations executed on a variable of atomic type are each atomic separately, but do not form one joint atomic operation).
An atomic type is declared as atomic<T>, where T is the non-atomic base type and must be trivially copyable (for example, atomic<int> is an atomic integer). GCC does not yet support any base type T, but only those that can be accessed atomically with the atomic instructions offered by the target architecture. This is not a significant limitation in practice, given that atomics are primarily designed to expose hardware primitives in an architecture-independent fashion; pointers and integrals that are not larger than a machine word on the target are supported as base types. Using base types that are not yet supported results in link-time errors.
The code generated for operations on atomic types, including the memory orders, implements the semantics specified in the C++11 standard. However, support for the C++11 memory model is still experimental, and for example GCC might not always preserve data-race freedom when optimizing code.
GCC also supports new built-ins for atomic memory accesses, which follow the design of the memory model and new atomic operations. The former set of synchronization built-ins (that is, those prefixed with __sync) are still supported.
Transactional Memory
Transactional Memory (TM) allows programs to declare that a piece of code is supposed to execute as a transaction, that is, virtually atomically and in isolation from other transactions. GCC's transactional memory runtime library, libitm, then ensures this atomicity guarantee when executing the compiled program. Compared to atomic memory accesses, it is a higher-level programming abstraction, because it is not limited to single memory locations, does not require special data types for the data it modifies, and because transactions can contain arbitrary code and be nested within other transactions (with some
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GCC implements transactions as specified in the Draft Specification for Transactional Language
Constructs for C++, version 1.1
. This draft does not yet specify the language constructs for C, but GCC already supports a C-compatible subset of the constructs when compiling C source code.
The main language constructs are transaction statements and expressions, and are declared by the
__transaction_atom ic or __transaction_relaxed keywords followed by a compound statement or expression, respectively. The following example illustrates how to increment a global variable y if another variable x has a value less than 10:
__transaction_atomic { if (x < 10 ) y++; }
This happens atomically even in a multi-threaded execution of the program. In particular, even though the transaction can load x and y and store to y, all these memory accesses are virtually executed as one indivisible step.
Note that in line with the C++11 memory model, programs that use transactions must be free of data races. Transactions are guaranteed to be virtually executed serially in a global total order that is determined by the transactional memory implementation and that is consistent with and contributes to the happens-before order enforced by the rest of the program (that is, transaction semantics are specified based on the C++11 memory model, see the draft specification linked above). Nonetheless, if a program is not data-race-free, then it has undefined behavior. For example, a thread can first initialize some data and then make it publicly accessible by code like this: init(data);
__transaction_atomic { data_public = true;} // data_public is initially false
Another thread can then safely use the data, for instance:
__transaction_atomic { if (data_public) use(data); }
However, the following code has a data race and thus results in undefined behavior:
__transaction_atomic { temp = copy(data); if (data_public) use(temp); }
Here, copy(data) races with init(data) in the initializing thread, because this can be executed even if data_public is not true. Another example for data races is one thread accessing a variable x transactionally and another thread accessing it nontransactionally at potentially the same time. Note that the data can be safely reclaimed using code like this (assuming only one thread ever does this):
__transaction_atomic { data_public = false ; } destruct(data);
Here, destruct() does not race with potential concurrent uses of the data because after the transaction finishes, it is guaranteed that data_public is false and thus data is private. See the specification and the C++11 memory model for more background information about this.
Note that even if transactions are required to virtually execute in a total order, this does not mean that they execute mutually exclusive in time. Transactional memory implementations attempt to run transactions as much in parallel as possible to provide scalable performance.
There are two variants of transactions: atomic transactions (__transaction_atomic) and relaxed
transactions (__transaction_relaxed). The former guarantee atomicity with regard to all other code,
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Changes in Version 2.0 but allow only code that is known to not include nontransactional kinds of synchronization, such as atomic or volatile memory access. In contrast, relaxed transactions allow all code (for example calls to I/O functions), but only provide atomicity with regard to other transactions. Therefore, atomic transactions can be nested within other atomic and relaxed transactions, but relaxed transactions can only be nested within other relaxed transactions. Furthermore, relaxed transactions are likely to be executed with less performance, but this depends on the implementation and available hardware.
GCC verifies these restrictions statically at compile time (for example, the requirements on code allowed to be called from within atomic transactions). This has implications for when transactions call functions that are defined within other compilation unit (source file) or within libraries. To enable such crosscompilation-unit calls for transactional code, the respective functions must be marked to contain code that is safe to use from within atomic transactions. Programmers can do so by adding the
transaction_safe function attribute to the declarations of these functions and by including this declaration when defining the function. In turn, GCC then verifies that the code in these functions is safe for atomic transactions and generates code accordingly. If the programmer does not follow these constraints and/or steps, compile-time or link-time errors occur. Note that within a compilation unit, GCC detects automatically whether a function is safe for use within transactions, and the attributes therefore typically do not need to be added. See the draft specification linked above for further details.
GCC's transactional memory support is designed in such a way that it does not decrease the performance of programs that do not use transactions, nor the performance of nontransactional code, except due to the normal kinds of interference by concurrent threads that use the same resources such as the CPU.
Transactional memory support in GCC and libitm is still experimental, and both the ABI and API could change in the future if this is required due to the evolution of the specification of the language constructs, or due to implementation requirements. Note that when executing applications built with the -
fgnu-tm command line option, it is currently a prerequisite to also have the appropriate version of the
libitm .so.1 shared library installed.
A.2.2.1.4 . Architecture-specific Options
Red Hat Developer Toolset 2.0 is only available for Red Hat Enterprise Linux 5 and 6, both for the 32-bit and 64-bit Intel and AMD architectures. Consequently, the options described below are only relevant to these architectures.
Optimization for several processors is now available through the command line options described in
Table A.1, “Processor Optimization Options” .
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Table A.1. Processor Optimization Options
Option
-m arch=core2 and -m tune=core2
-m arch=corei7 and -m tune=corei7
-m arch=corei7-avx and -m tune=corei7-
avx
-m arch=core-avx-i
-m arch=core-avx2
-m arch=bdver2 and -m tune=bdver2
-m arch=btver1 and -m tune=btver1
-m arch=bdver1 and -m tune=bdver1
Description
Optimization for Intel Core 2 processors.
Optimization for Intel Core i3, i5, and i7 processors.
Optimization for Intel Core i3, i5, and i7 processors with AVX.
Optimization for the Intel processor code-named
Ivy Bridge with RDRND, FSGSBASE, and F16C.
Optimization for a next-generation processor from
Intel with AVX2, FMA, BMI, BMI2, and LZCNT.
Optimization for AMD Opteron processors codenamed Piledriver.
Optimization for AMD family 14 processors codenamed Bobcat.
Optimization for AMD family 15h processors code-named Bulldozer.
Support for various processor-specific intrinsics and instructions is now available through the command
line options described in Table A.2, “Support for Processor-specific Intrinsics and Instructions”
.
Table A.2. Support for Processor-specific Intrinsics and Instructions
Option
-m avx2
-m bm i2
-m lzcnt
-m fm a
-m fsgsbase
-m rdrnd
-m f16c
-m tbm
-m bm i
-m crc32
-m m ovbe
-m xop, -m fm a4 , and -
m lwp
-m abm
-m popcnt
Description
Support for Intel AVX2 intrinsics, built-in functions, and code generation.
Support for Intel BMI2 intrinsics, built-in functions, and code generation.
Implementation and automatic generation of __builtin_clz* using the
lzcnt instruction.
Support for Intel FMA3 intrinsics and code generation.
Enables the generation of new segment register read/write instructions through dedicated built-ins.
Support for the Intel rdrnd instruction.
Support for two additional AVX vector conversion instructions.
Support for TBM (Trailing Bit Manipulation) built-in functions and code generation.
Support for AMD's BMI (Bit Manipulation) built-in functions and code generation.
Support for crc32 intrinsics.
Enables the use of the movbe instruction to implement
__builtin_bswap32 and __builtin_bswap64 .
Support for the XOP, FMA4, and LWP instruction sets for the AMD Orochi processors.
Enables the use of the popcnt and lzcnt instructions on AMD processors.
Enables the use of the popcnt instruction on both AMD and Intel processors.
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Changes in Version 2.0
When using the x87 floating-point unit, GCC now generates code that conforms to ISO C99 in terms of handling of floating-point excess precision. This can be enabled by -fexcess-precision=standard and disabled by -fexcess-precision=fast. This feature is enabled by default when using standards conformance options such as -std=c99.
Vectors of type vector long long or vector long are passed and returned using the same method as other vectors with the VSX instruction set. Previously GCC did not adhere to the ABI for 128bit vectors with 64-bit integer base types (see GCC PR 48857).
The -mrecip command line option has been added, which indicates whether the reciprocal and reciprocal square root instructions should be used.
The -mveclibabi=mass command line option has been added. This can be used to enable the compiler to auto-vectorize mathematical functions using the Mathematical Acceleration Subsystem library.
The -msingle-pic-base command line option has been added, which instructs the compiler to avoid loading the PIC base register in function prologues. The PIC base register must be initialized by the runtime system.
The -mblock-move-inline-limit command line option has been added, which enables the user to control the maximum size of inlined memcpy calls and similar.
A.2.2.1.5. Link-time Optimization
Link-time optimization (LTO) is a compilation technique in which GCC generates an internal representation of each compiled input file in addition to the native code, and writes both to the output object file. Subsequently, when several object files are linked together, GCC uses the internal representations of the compiled code to optimize inter-procedurally across all the compilation units. This can potentially improve the performance of the generated code (for example, functions defined in one file can potentially be inlined when called in another file).
To enable LTO, the -flto option needs to be specified at both compile time and link time. For further details, including interoperability with linkers and parallel execution of LTO, refer to the documentation for
-flto in the
GCC 4.7.0 Manual . Also note that the internal representation is not a stable interface, so
LTO will only apply to code generated by the same version of GCC.
Note
Use of Link-time Optimization with debug generation is not yet supported in gcc 4.7 and 4.8 and so use of the -flto and the -g options together is unsupported in Red Hat Developer Toolset.
A.2.2.1.6. Miscellaneous
-Ofast is now supported as a general optimization level. It operates similar to -O3, adds options that can yield better-optimized code, but in turn might invalidate standards compliance (for example, -ffast-
m ath is enabled by -Ofast).
GCC can now inform users about cases in which code generation might be improved by adding attributes such as const, pure, and noreturn to functions declared in header files. Use the -
Wsuggest-attribute=[const|pure|noreturn] command line option to enable this.
Assembler code can now make use of a goto feature that allows for jumps to labels in C code.
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A.2.2.2. Language Compatibility
In this section, we describe the compatibility between the Red Hat Developer Toolset compilers and the
Red Hat Enterprise Linux system compilers at the programming-language level (for example, differences in the implementation of language standards such as C99, or changes to the warnings generated by -
Wall).
Some of the changes are a result of bug fixing, and some old behaviors have been intentionally changed in order to support new standards, or relaxed in standards-conforming ways to facilitate compilation or runtime performance. Some of these changes are not visible to the naked eye and will not cause problems when updating from older versions. However, some of these changes are visible, and can cause grief to users porting to Red Hat Developer Toolset's version of GCC. The following text attempts to identify major issues and suggests solutions.
A.2.2.2.1. C
Constant expressions are now handled by GCC in a way that conforms to C90 and C99. For code expressions that can be transformed into constants by the compiler but are in fact not constant expressions as defined by ISO C, this may cause warnings or errors.
Ill-formed redeclarations of library functions are no longer accepted by the compiler. In particular, a function with a signature similar to the built-in declaration of a library function (for example, abort() or
m em cpy()) must be declared with extern "C" to be considered as a redeclaration, otherwise it is illformed.
Duplicate Member
Consider the following struct declaration: struct A { int *a; union { struct { int *a; }; }; };
Previously, this declaration used to be diagnosed just by the C++ compiler, now it is also diagnosed by the C compiler. Because of the anonymous unions and structs, there is ambiguity about what .a actually refers to and one of the fields therefore needs to be renamed.
A.2.2.2.2. C++
Header Dependency Changes
<iostream >, <string>, and other STL headers that previously included <unistd.h> as an implementation detail (to get some feature macros for gthr*.h purposes) no longer do so, because it was a C++ standard violation. This can result in diagnostic output similar to the following: error: ‘truncate’ was not declared in this scope error: ‘sleep’ was not declared in this scope error: ‘pipe’ was not declared in this scope error: there are no arguments to 'offsetof' that depend on a template parameter, so a declaration of 'offsetof' must be available
To fix this, add the following line early in the source or header files that need it:
#include <unistd.h>
Many of the standard C++ library include files have been edited to no longer include <cstddef> to get namespace-std-scoped versions of size_t and ptrdiff_t. As such, C++ programs that used the
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Changes in Version 2.0 macros NULL or offsetof without including <cstddef> will no longer compile. The diagnostic produced is similar to the following: error: 'ptrdiff_t' does not name a type error: 'size_t' has not been declared error: 'NULL' was not declared in this scope error: there are no arguments to 'offsetof' that depend on a template parameter, so a declaration of 'offsetof' must be available
To fix this issue, add the following line:
#include <cstddef>
Name Lookup Changes
G++ no longer performs an extra unqualified lookup that it incorrectly performed in the past. Instead, it implements the two-phase lookup rules correctly, and an unqualified name used in a template must have an appropriate declaration that:
1. is either in scope at the point of the template's definition, or
2. can be found by argument-dependent lookup at the point of instantiation.
Code that incorrectly depends on a second unqualified lookup at the point of instantiation (such as finding functions declared after the template or in dependent bases) will result in compile-time errors.
In some cases, the diagnostics provided by G++ include hints how to fix the bugs. Consider the following code: template<typename T> int t(T i)
{ return f(i);
} int f( int i)
{ return i;
} int main()
{ return t( 1 );
}
The following diagnostics output will be produced:
In instantiation of ‘int t(T) [with T = int]’ required from here error: ‘f’ was not declared in this scope, and no declarations were found by argument-dependent lookup at the point of instantiation [-fpermissive] note: ‘int f(int)’ declared here, later in the translation unit
To correct the error in this example, move the declaration of function f() before the definition of template function t(). The -fpermissive compiler flag turns compile-time errors into warnings and can be used as a temporary workaround.
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Uninitialized const
Consider the following declaration: struct A { int a; A (); }; struct B : public A { }; const B b;
An attempt to compile this code now fails with the following error: error: uninitialized const ‘b’ [-fpermissive] note: ‘const struct B’ has no user-provided default constructor
This happens, because B does not have a user-provided default constructor. Either an initializer needs to be provided, or the default constructor needs to be added.
Visibility of Template Instantiations
The ELF symbol visibility of a template instantiation is now properly constrained by the visibility of its template arguments. For instance, users that instantiate standard library components like std::vector with hidden user defined types such as struct my_hidden_struct can now expect hidden visibility for std::vector<my_hidden_struct> symbols. As a result, users that compile with the -
fvisibility=hidden command line option should be aware of the visibility of types included from the library headers used. If the header does not explicitly control symbol visibility, types from those headers will be hidden, along with instantiations that use those types. For instance, consider the following code:
#include <vector> // template std::vector has default visibility
#include <ctime> // struct tm has hidden visibility template class std::vector<tm>; // instantiation has hidden visibility
One approach to adjusting the visibility of a library header <foo.h> is to create a forwarding header on the -I include path consisting of the following:
#pragma GCC visibility push(default)
#include_next <foo.h>
#pragma GCC visibility push
User-defined Literal Support
When compiling C++ with the -std={c++11,c++0x,gnu++11,gnu++0x} command line option, GCC
4.7.0 and later, unlike older versions, supports user-defined literals, which are incompatible with some valid ISO C++03 code. In particular, white space is now needed after a string literal before something that could be a valid user defined literal. Consider the following code: const char *p = "foobar" __TIME__;
In C++03, the __TIME__ macro expands to some string literal and is concatenated with the other one. In
C++11, __TIME__ is not expanded and instead, operator "" __TIME__ is being looked up, which results in a warning like: error: unable to find string literal operator ‘operator"" __TIME__’
This applies to any string literal followed without white space by some macro. To fix this, add some white space between the string literal and the macro name.
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Taking the Address of Temporary
Consider the following code: struct S { S (); int i; }; void bar (S *); void foo () { bar (&S ()); }
Previously, an attempt to compile this code produced a warning message, now it fails with an error. This can be fixed by adding a variable and passing the address of this variable instead of the temporary. The
-fperm issive compiler flag turns compile-time errors into warnings and can be used as a temporary workaround.
Miscellaneous
G++ now sets the predefined macro __cplusplus to the correct value: 199711L for C++98/03, and
201103L for C++11.
G++ now properly re-uses stack space allocated for temporary objects when their lifetime ends, which can significantly lower stack consumption for some C++ functions. As a result of this, some code with undefined behavior will now break.
When an extern declaration within a function does not match a declaration in the enclosing context, G++ now properly declares the name within the namespace of the function rather than the namespace which was open just before the function definition.
G++ now implements the proposed resolution of the C++ standard's core issue 253. Default initialization is allowed if it initializes all subobjects, and code that fails to compile can be fixed by providing an initializer such as: struct A { A(); }; struct B : A { int i; }; const B b = B();
Access control is now applied to typedef names used in a template, which may cause G++ to reject some ill-formed code that was accepted by earlier releases. The -fno-access-control option can be used as a temporary workaround until the code is corrected.
G++ now implements the C++ standard's core issue 176. Previously, G++ did not support using the injected-class-name of a template base class as a type name, and lookup of the name found the declaration of the template in the enclosing scope. Now lookup of the name finds the injected-classname, which can be used either as a type or as a template, depending on whether or not the name is followed by a template argument list. As a result of this change, some code that was previously accepted may be ill-formed, because:
1. the injected-class-name is not accessible because it is from a private base, or
2. the injected-class-name cannot be used as an argument for a template parameter.
In either of these cases, the code can be fixed by adding a nested-name-specifier to explicitly name the template. The first can be worked around with -fno-access-control, the second is only rejected with -pedantic.
A.2.2.2.3. C/C++ Warnings
GCC 4.7.0 and later adds a number of new warnings that are either enabled by default, or by using the -
Wall option. Although these warnings do not result in a compilation failure on their own, often -Wall is
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C++.
The behavior of the -Wall command line option has changed and now includes the new warning flags -
Wunused-but-set-variable and, with -Wall -Wextra, -Wunused-but-set-param eter. This may result in new warnings in code that compiled cleanly with previous versions of GCC. For example, consider the following code: void fn ( void )
{ int foo;
foo = bar (); /* foo is never used. */
}
The following diagnostic output will be produced: warning: variable "foo" set but not used [-Wunused-but-set-variable]
To fix this issue, first see if the unused variable or parameter can be removed without changing the result or logic of the surrounding code. If not, annotate it with __attribute__((__unused__)). As a workaround, you can use the -Wno-error=unused-but-set-variable or -Wno-error=unused-
but-set-param eter command line option.
The -Wenum-compare option causes GCC to report a warning when values of different enum types are being compared. Previously, this option only worked for C++ programs, but now it works for C as well. This warning is enabled by -Wall and may be avoided by using a type cast.
Casting integers to larger pointer types now causes GCC to display a warning by default. To disable these warnings, use the -Wno-int-to-pointer-cast option, which is available for both C and C++.
Conversions between NULL and non-pointer types now cause GCC to report a warning by default.
Previously, these warnings were only displayed when explicitly using -Wconversion. To disable these warnings, use the new -Wno-conversion-null command line option.
GCC can now warn when a class that has virtual functions and a non-virtual destructor is destroyed by using delete. This is unsafe to do because the pointer might refer to a base class that does not have a virtual destructor. The warning is enabled by -Wall and by a new command line option, -Wdelete-
non-virtual-dtor.
New -Wc++11-compat and -Wc++0x-compat options are now available. These options cause GCC to display a warning about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++
2011 (such as identifiers in ISO C++ 1998 that are keywords in ISO C++ 2011). This warning is enabled by -Wall and enables the -Wnarrowing option.
A.2.2.2.4 . Fortran
A.2.2.2.4 .1. New Features
A new compile flag -fstack-arrays has been added. This flag causes all local arrays to be put on stack memory, which can significantly improve the performance of some programs. Note that programs that use very large local arrays may require you to extend your runtime limits for stack memory.
Compile time has been significantly improved. For example, the improvement may be noticeable when
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To improve code generation and diagnostics, the -fwhole-file compile flag is now enabled by default, and can be used with a newly supported -fwhole-program flag. To disable it, use the deprecated -fno-whole-file flag.
A new command line option -M is now supported. Similarly to gcc, this option allows you to generate
Makefile dependencies. Note that the -cpp option may be required as well.
The -finit-real= command line option now supports snan as a valid value. This allows you to initialize REAL and COMPLEX variables with a signaling NaN (not a number), and requires you to enable trapping (for example, by using the -ffpe-trap= command line option). Note that compiletime optimizations may turn a signaling NaN into a quiet NaN.
A new command line option -fcheck= has been added. This option accepts the following arguments:
The -fcheck=bounds option is equivalent to the -fbounds-check command line option.
The -fcheck=array-temps option is equivalent to the -fcheck-array-temporaries command line option.
The -fcheck=do option checks for invalid modification of loop iteration variables.
The -fcheck=recursive option checks for recursive calls to subroutines or functions that are not marked as recursive.
The -fcheck=pointer option performs pointer association checks in calls, but does not handle undefined pointers nor pointers in expressions.
The -fcheck=all option enables all of the above options.
A new command line option -fno-protect-parens has been added. This option allows the compiler to reorder REAL and COMPLEX expressions with no regard to parentheses.
When OpenMP's WORKSHARE is used, array assignments and WHERE will now be run in parallel.
More Fortran 2003 and Fortran 2008 mathematical functions can now be used as initialization expressions.
The GCC$ compiler directive now enables support for some extended attributes such as STDCALL.
A.2.2.2.4 .2. Compatibility Changes
The -Ofast command line option now automatically enables the -fno-protect-parens and -
fstack-arrays flags.
Front-end optimizations can now be disabled by the -fno-frontend-optimize option, and selected by the -ffrontend-optimize option. The former is essentially only desirable if invalid
Fortran source code needs to be compiled (for example, when functions—as compared to subroutines—have side-effects) or to work around compiler bugs.
The GFORTRAN_USE_STDERR environment variable has been removed, and GNU Fortran now always prints error messages to standard error.
The -fdump-core command line option and the GFORTRAN_ERROR_DUMPCORE environment variable have been removed. When encountering a serious error, GNU Fortran now always aborts the execution of the program.
The -fbacktrace command line option is now enabled by default. When a fatal error occurs, GNU
Fortran now attempts to print a backtrace to standard error before aborting the execution of the program. To disable this behavior, use the -fno-backtrace option.
GNU Fortran no longer supports the use of the -M command line option to generate Makefile dependencies for the module path. To perform this operation, use the -J option instead.
To significantly reduce the number of warnings, the -Wconversion command line option now only
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Wconversion-extra has been added to display warnings about other conversions. The -
Wconversion option is now enabled with -Wall.
A new command line option -Wunused-dummy-argument has been added. This option can be used to display warnings about unused dummy arguments, and is now enabled with -Wall. Note that the -Wunused-variable option previously also warned about unused dummy arguments.
The COMMON default padding has been changed. Previously, the padding was added before a variable. Now it is added after a variable to increase the compatibility with other vendors, as well as to help to obtain the correct output in some cases. Note that this behavior is in contrast with the behavior of the -falign-commons option.
GNU Fortran no longer links against the libgfortranbegin library. The MAIN__ assembler symbol is the actual Fortran main program and is invoked by the main function, which is now generated and put in the same object file as MAIN__. Note that the libgfortranbegin library is still present for backward compatibility.
A.2.2.2.4 .3. Fortran 2003 Features
Improved but still experimental support for polymorphism between libraries and programs and for complicated inheritance patterns.
Generic interface names which have the same name as derived types are now supported, which allows the creation of constructor functions. Note that Fortran does not support static constructor functions; only default initialization or an explicit structure-constructor initialization are available.
Automatic (re)allocation: In intrinsic assignments to allocatable variables, the left-hand side will be automatically allocated (if unallocated) or reallocated (if the shape or type parameter is different). To avoid the small performance penalty, you can use a(:) = ... instead of a = ... for arrays and character strings — or disable the feature using -std=f95 or -fno-realloc-lhs.
Experimental support of the ASSOCIATE construct has been added.
In pointer assignments it is now possible to specify the lower bounds of the pointer and, for a rank-1 or a simply contiguous data-target, to remap the bounds.
Deferred type parameter: For scalar allocatable and pointer variables the character length can now be deferred.
Namelist variables with allocatable attribute, pointer attribute, and with a non-constant length type parameter are now supported.
Support has been added for procedure-pointer function results and procedure-pointer components
(including PASS).
Support has been added for allocatable scalars (experimental), DEFERRED type-bound procedures, and the ERRMSG= argument of the ALLOCATE and DEALLOCATE statements.
The ALLOCATE statement now supports type-specs and the SOURCE= argument.
Rounding (ROUND=, RZ, ...) for output is now supported.
The INT_FAST{8,16,32,64,128}_T format for ISO_C_BINDING intrinsic module type parameters is now supported.
OPERAT OR(* ) and ASSIGNMENT (=) are now allowed as GENERIC type-bound procedures (i.e. as type-bound operators).
A.2.2.2.4 .4 . Fortran 2003 Compatibility
Extensible derived types with type-bound procedure or procedure pointer with PASS attribute now have to use CLASS in line with the Fortran 2003 standard; the workaround to use TYPE is no longer supported.
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A.2.2.2.4 .5. Fortran 2008 Features
A new command line option -std=f2008ts has been added. This option enables support for programs that conform to the Fortran 2008 standard and the draft Technical Specification (TS)
29113 on Further Interoperability of Fortran with C. For more information, refer to the Chart of Fortran
TS 29113 Features supported by GNU Fortran .
The DO CONCURRENT construct is now supported. This construct can be used to specify that individual loop iterations do not have any interdependencies.
Full single-image support except for polymorphic coarrays has been added, and can be enabled by using the -fcoarray=single command line option. Additionally, GNU Fortran now provides preliminary support for multiple images via an MPI-based coarray communication library. Note that the library version is not yet usable as remote coarray access is not yet possible.
The STOP and ERROR STOP statements have been updated to support all constant expressions.
The CONTIGUOUS attribute is now supported.
Use of ALLOCATE with the MOLD argument is now supported.
The STORAGE_SIZE intrinsic inquiry function is now supported.
The NORM2 and PARITY intrinsic functions are now supported.
The following bit intrinsics have been added: the POPCNT and POPPAR bit intrinsics for counting the number of 1 bits and returning the parity; the BGE, BGT, BLE, and BLT bit intrinsics for bitwise comparisons; the DSHIFTL and DSHIFTR bit intrinsics for combined left and right shifts; the MASKL and MASKR bit intrinsics for simple left and right justified masks; the MERGE_BITS bit intrinsic for a bitwise merge using a mask; the SHIFTA, SHIFTL, and SHIFTR bit intrinsics for shift operations; the transformational bit intrinsics IALL, IANY, and IPARITY.
The EXECUTE_COMMAND_LINE intrinsic subroutine is now supported.
The IMPURE attribute for procedures is now supported. This allows the use of ELEMENTAL procedures without the restrictions of PURE.
Null pointers (including NULL()) and unallocated variables can now be used as an actual argument to optional non-pointer, non-allocatable dummy arguments, denoting an absent argument.
Non-pointer variables with the TARGET attribute can now be used as an actual argument to
POINT ER dummies with INT ENT (IN).
Pointers that include procedure pointers and those in a derived type (pointer components) can now also be initialized by a target instead of only by NULL.
The EXIT statement (with construct-name) can now be used to leave the ASSOCIATE, BLOCK, IF,
SELECT CASE, and SELECT T YPE constructs in addition to DO.
Internal procedures can now be used as actual arguments.
The named constants INTEGER_KINDS, LOGICAL_KINDS, REAL_KINDS, and CHARACTER_KINDS of the intrinsic module ISO_FORTRAN_ENV have been added. These arrays contain the supported
'kind' values for the respective types.
The C_SIZEOF module procedures of the ISO_C_BINDINGS intrinsic module and the
COMPILER_VERSION and COMPILER_OPT IONS module procedures of the ISO_FORT RAN_ENV intrinsic module have been implemented.
The OPEN statement now supports the NEWUNIT= option. This option returns a unique file unit and therefore prevents inadvertent use of the same unit in different parts of the program.
Unlimited format items are now supported.
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The INT{8,16,32} and REAL{32,64,128} format for ISO_FORTRAN_ENV intrinsic module type parameters are now supported.
It is now possible to use complex arguments with the TAN, SINH, COSH, TANH, ASIN, ACOS, and
AT AN functions. Additionally, the new functions ASINH, ACOSH, and AT ANH have been added for real and complex arguments, and ATAN(Y,X) now serves as an alias for ATAN2(Y,X).
The BLOCK construct has been implemented.
A.2.2.2.4 .6. Fortran 2008 Compatibility
The implementation of the ASYNCHRONOUS attribute in GCC is now compatible with the candidate draft of TS 29113: Technical Specification on Further Interoperability with C.
A.2.2.2.4 .7. Fortran 77 Compatibility
When the GNU Fortran compiler is issued with the -fno-sign-zero option, the SIGN intrinsic now behaves as if zero were always positive.
A.2.2.3. ABI Compatibility
This section describes compatibility between the Red Hat Developer Toolset compilers and the system compilers at the application binary interface (ABI) level.
A.2.2.3.1. C++ ABI
Because the upstream GCC community development does not guarantee C++11 ABI compatibility across major versions of GCC, the same applies to use of C++11 with Red Hat Developer Toolset.
Consequently, using the -std=c++11 option is supported in Red Hat Developer Toolset 2.0 only when all C++ objects compiled with that flag have been built using the same major version of Red Hat
Developer Toolset. The mixing of objects, binaries and libraries, built by the Red Hat Enterprise Linux 5 or 6 system toolchain GCC using the -std=c++0x or -std=gnu++0x flags, with those built with the -
std=c++11 or -std=gnu++11 flags using the GCC in Red Hat Developer Toolset is explicitly not supported.
As later major versions of Red Hat Developer Toolset may use a later major release of GCC, forwardcompatibility of objects, binaries, and libraries built with the -std=c++11 or -std=gnu++11 options cannot be guaranteed, and so is not supported.
The default language standard setting for Red Hat Developer Toolset is C++98. Any C++98-compliant binaries or libraries built in this default mode (or explicitly with -std=c++98) can be freely mixed with binaries and shared libraries built by the Red Hat Enterprise Linux 5 or 6 system toolchain GCC. Red
Hat recommends use of this default -std=c++98 mode for production software development.
Important
Use of C++11 features in your application requires careful consideration of the above ABI compatibility information.
Aside from the C++11 ABI, discussed above, the Red Hat Enterprise Linux Application Compatibility
Specification is unchanged for Red Hat Developer Toolset. When mixing objects built with Red Hat
Developer Toolset with those built with the Red Hat Enterprise Linux v5.x/v6.x toolchain (particularly .o/.a
files), the Red Hat Developer Toolset toolchain should be used for any linkage. This ensures any newer library features provided only by Red Hat Developer Toolset are resolved at link-time.
A new standard mangling for SIMD vector types has been added to avoid name clashes on systems with
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A.2.2.3.2. Miscellaneous
GCC now optimizes calls to various standard C string functions such as strlen(), strchr(),
strcpy(), strcat() and stpcpy() (as well as their respective _FORT IFY_SOURCE variants) by transforming them into custom, faster code. This means that there might be fewer or other calls to those functions than in the original source code. The optimization is enabled by default at -O2 or higher optimization levels. It is disabled when using -fno-optimize-strlen or when optimizing for size.
When compiling for 32-bit GNU/Linux and not optimizing for size, -fomit-frame-pointer is now enabled by default. The prior default setting can be chosen by using the -fno-omit-frame-pointer command line option.
Floating-point calculations on x86 targets and in strict C99 mode are now compiled by GCC with a stricter standard conformance. This might result in those calculations executing significantly slower. It can be disabled using -fexcess-precision=fast.
A.2.2.4 . Debugging Compatibility
GCC now generates DWARF debugging information that uses more or newer DWARF features than previously. GDB contained in Red Hat Developer Toolset can handle these features, but versions of
GDB older than 7.0 cannot. GCC can be restricted to only generate debugging information with older
DWARF features by using the -gdwarf-2 -gstrict-dwarf or -gdwarf-3 -gstrict-dwarf options (the latter are handled partially by versions of GDB older than 7.0).
Many tools such as Valgrind, SystemTap, or third-party debuggers utilize debugging information. It is suggested to use the -gdwarf-2 -gstrict-dwarf options with those tools.
Note
Use of Link-time Optimization with debug generation is not yet supported in gcc 4.7 and 4.8 and so use of the -flto and the -g options together is unsupported in Red Hat Developer Toolset.
A.2.2.5. Other Compatibility
GCC is now more strict when parsing command line options, and both gcc and g++ report an error when invalid command line options are used. In particular, when only linking and not compiling code, earlier versions of GCC ignored all options starting with --. For example, options accepted by the linker such as --as-needed and --export-dynamic are not accepted by gcc and g++ anymore, and should now be directed to the linker using -Wl,--as-needed or -Wl,--export-dynamic if that is intended.
Because of the new link-time optimization feature (see Section A.2.2.1.5, “Link-time Optimization”
), support for the older intermodule optimization framework has been removed and the -combine command line option is not accepted anymore.
A.3. Changes in binutils
Red Hat Developer Toolset 2.0 is distributed with binutils 2.23.52, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version
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The GNU assembler (as), GNU linker (ld), and other binary tools that are part of binutils are now released under the GNU General Public License, version 3.
A.3.1. GNU Linker
Another ELF linker, gold, is now available in addition to ld, the existing GNU linker. gold is intended to be a drop-in replacement for ld, so ld's documentation is intended to be the reference documentation.
gold supports most of ld's features, except notable ones such as MRI-compatible linker scripts, crossreference reports (--cref), and various other minor options. It also provides significantly improved link time with very large C++ applications.
In Red Hat Developer Toolset 2.0, the gold linker is not enabled by default. Users can explicitly switch between ld and gold by using the alternatives mechanism.
A.3.1.1. New Features
Changes Since Red Hat Enterprise Linux 6.4
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 6.4:
A new INPUT_SECTION_FLAGS keyword has been added to the linker script language. This keyword can be used to select input sections by section header flags.
A new SORT_BY_INIT_PRIORITY keyword has been added to the linker script language. This keyword can be used to sort sections by numerical value of the GCC init_priority attribute encoded in the section name.
A new SORT_NONE keyword has been added to the linker script language. This keyword can be used to disable section sorting.
A new linker-provided symbol, __ehdr_start, has been added. When producing ELF output, this symbol points to the ELF file header (and nearby program headers) in the program's memory image.
Changes Since Red Hat Enterprise Linux 5.9
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 5.9:
GNU/Linux targets now support the STB_GNU_UNIQUE symbol binding, a GNU extension to the standard set of ELF symbol bindings. The binding is passed on to the dynamic linker, which ensures that in the entire process there is only one symbol with the given name and type in use.
Note
The implementation of this feature depends on capabilities only found in newer versions of the glibc library. Consequently, this feature is currently available in Red Hat Developer
Toolset for Red Hat Enterprise Linux 6.
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A new command line option --no-export-dynamic has been added. This option can be used to undo the effect of the -E and --export-dynamic options.
A new command line option --warn-alternate-em has been added. This option can be used to display a warning if an ELF format object file uses an alternate machine code.
A new linker script function REGION_ALIAS has been added. This function can be used to create
Changes in Version 2.0 alias names of memory regions.
A new command line option -Ttext-segment address has been added for ELF-based targets.
This option can be used to set the address of the first byte of the text segment.
A new linker script command INSERT has been added. This command can be used to augment the default script.
In a linker script input section, it is now possible to specify a file within an archive by using the
archive:file syntax.
The --sort-common command line option now accepts ascending and descending as optional arguments. This can be used to specify which sorting order to use.
A new command line option --build-id has been added for ELF-based targets. This option can be used to generate a unique per-binary identifier embedded in a note section.
A new command line option --default-script=file_name (or -dT file_name) has been added. This option can be used to specify a replacement for the built-in linker script.
A new command line option -Bsymbolic-functions has been added. When creating a shared library, this option will cause references to global function symbols to be bound to the definitions with the shared library, if such exist.
The new command line options --dynamic-list-cpp-new and --dynamic-list-data have been added, which can be used to modify the dynamic list.
A.3.1.2. Compatibility Changes
Changes Since Red Hat Enterprise Linux 6.4
The following compatibility changes have been made since the release of binutils included in Red Hat
Enterprise Linux 6.4:
The --copy-dt-needed-entries command line option is no longer enabled by default. Instead, -
-no-copy-dt-needed-entries is now the default option.
Evaluation of linker script expressions has been significantly improved. Note that this can negatively affect scripts that rely on undocumented behavior of the old expression evaluation.
Changes Since Red Hat Enterprise Linux 5.9
The following compatibility changes have been made since the release of binutils included in Red Hat
Enterprise Linux 5.9:
The --add-needed command line option has been renamed to --copy-dt-needed-entries in order to avoid confusion with the --as-needed option.
For GNU/Linux systems, the linker no longer processes any relocations made against symbols of the
ST T _GNU_IFUNC type. Instead, it emits them into the resulting binary for processing by the loader.
Note
The implementation of this feature depends on capabilities only found in newer versions of the glibc library. Consequently, this feature is currently available in Red Hat Developer
Toolset for Red Hat Enterprise Linux 6.
The --as-needed command line option has been adapted to link in a dynamic library in the following two cases:
1. if the dynamic library satisfies undefined symbols in regular objects, and
2. if the dynamic library satisfies undefined symbols in other dynamic libraries unless the library
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The -l:file_name command line option now searches the library path for a file name called
file_name without adding the .a or .so file extension.
A.3.2. GNU Assembler
A.3.2.1. New Features
Changes Since Red Hat Enterprise Linux 6.4
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 6.4:
The GNU Assembler no longer requires double ampersands in macros.
A new --compress-debug-sections command line option has been added to enable compression of DWARF debug information sections in the relocatable output file. Compressed debug sections are currently supported by the readelf, objdump, and gold tools, but not by ld.
Support for .bundle_align_mode, .bundle_lock, and .bundle_unlock directives for x86 targets has been added..
On x86 architectures, the GNU Assembler now allows rep bsf, rep bsr, and rep ret syntax.
Changes Since Red Hat Enterprise Linux 5.9
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 5.9:
GNU/Linux targets now support gnu_unique_object as a value of the .type pseudo operation.
This value can be used to mark a symbol as globally unique in the entire process.
Support for the new discriminator column in the DWARF line table with a discriminator operand for the
.loc directive has been added.
The .type pseudo operation now accepts a type of STT_GNU_IFUNC. This can be used to indicate that if the symbol is the target of a relocation, its value should not be used. Instead, the function should be invoked and its result used as the value.
A new pseudo operation .cfi_val_encoded_addr has been added. This pseudo operation can be used to record constant addresses in unwind tables without runtime relocation.
A new command line option -msse-check=[none|error|warning] has been added for x86 targets.
The -a command line option now accepts g as a valid sub-option. This combination can be used to enable assembly listings with additional information about the assembly, including the list of supplied command line options or the assembler version.
A new command line option -msse2avx has been added for x86 targets. This option can be used to encode SSE instructions with VEX prefix.
x86 targets now support the Intel XSAVE, EPT, MOVBE, AES, PCLMUL, and AVX/FMA instructions.
New command line options -march=cpu[,+extension…], -mtune=cpu, -
m m nem onic=[att|intel], -m syntax=[att|intel], -m index-reg, -m naked-reg, and -
m old-gcc have been added for x86 targets.
New pseudo operations .string16, .string32, and .string64 have been added. These pseudo operations be used to generate wide character strings.
The i386 port now supports the SSE5 instruction set.
A new pseudo operation .reloc has been added. This pseudo operation serves as a low-level
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A.3.3. Other Binary Tools
A.3.3.1. New Features
Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of binutils included in Red Hat Developer
Toolset 1.1:
A manual page for the dwp utility has been added.
The binary tools now provide support for the AMD Family 15h processors, models 02h and 10-1fh.
Changes Since Red Hat Enterprise Linux 6.4
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 6.4:
The readelf and objdump tools can now display the contents of the .debug.macro sections.
New --dwarf-start and --dwarf-end command line options have been added to the readelf and objdump tools. These options are used by the new Emacs mode (see the dwarf-mode.el file).
A new --interleave-width command line option has been added to the objcopy tool to allow the use of the --interleave to copy a range of bytes from the input to the output.
A new --dyn-syms command line option has been added to the readelf tool. This option can be used to dump dynamic symbol table.
A new tool, elfedit, has been added to binutils. This tool can be used to directly manipulate ELF format binaries.
A new command line option --addresses (or -a for short) has been added to the addr2line tool. This option can be used to display addresses before function and source file names.
A new command line option --pretty-print (or -p for short) has been added to the addr2line tool. This option can be used to produce human-readable output.
Support for dwz -m optimized debug information has been added.
The devtoolset-2-binutils-devel package now provides the demangle.h header file.
Changes Since Red Hat Enterprise Linux 5.9
The following features have been added since the release of binutils included in Red Hat Enterprise
Linux 5.9:
A new command line option --insn-width=width has been added to the objdump tool. This option can be used to specify the number of bytes to be displayed on a single line when disassembling instructions.
A new command line option --relocated-dump=name|number has been added to the readelf tool. This option can be used to display the relocated contents of a section as a sequence of bytes.
A new command line option --external-symbols-table=filename has been added to the
gprof tool. This option can be used to read a symbol table from a certain file.
bfd now supports a plugin target, which can be used to get basic support for new file formats by having the plugin target load the same shared objects used by gold.
The --dwarf (or -W for short) command line option of the objdump tool has been adapted to be as flexible as the --debug-dump (or -w) option of readelf.
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New command line options --prefix=prefix and --prefix-strip=level have been added to the objdump tool. These options can be used to add absolute paths for the --source (or -S for short) option.
A new command line option -wL has been added to the readelf tool. This option can be used to dump decoded contents of the .debug_line section.
“Thin” archives are now supported. Instead of containing object files, such archives contain just pathnames pointing to those files.
A new command line option -F has been added to the objdump tool. This option can be used to include file offsets in the disassembly.
A new command line option -c has been added to the readelf tool. This option can be used to allow string dumps of archive symbol index.
The i386 port now supports the SSE5 instruction set.
A new command line option -p has been added to the readelf tool. This option can be used to allow string dumps of sections.
A.3.3.2. Compatibility Changes
Changes Since Red Hat Enterprise Linux 5.9
The following compatibility changes have been made since the release of binutils included in Red Hat
Enterprise Linux 5.9:
The --as-needed command line option has been adapted to link in a dynamic library in the following two cases:
1. if the dynamic library satisfies undefined symbols in regular objects, and
2. if the dynamic library satisfies undefined symbols in other dynamic libraries unless the library is already found in a DT_NEEDED entry of one of the libraries that are already linked.
A.4. Changes in elfutils
Red Hat Developer Toolset 2.0 is distributed with elfutils 0.155, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer Toolset 1.1. Below is a comprehensive list of new features in this release.
A.4.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of elfutils included in Red Hat Developer
Toolset 1.1:
In the libdw library, the DW_LANG_Objc constant has been correctly renamed to DW_LANG_ObjC.
Note that any existing source code that uses the old name needs to be updated accordingly.
The libdw library now supports new constants DW_ATE_UTF and DW_OP_GNU_parameter_ref.
In addition, it also defines a family of constants to support the .debug_macro section, namely
DW_MACRO_GNU_define, DW_MACRO_GNU_undef, DW_MACRO_GNU_start_file,
DW_MACRO_GNU_end_file, DW_MACRO_GNU_define_indirect,
DW_MACRO_GNU_undef_indirect, and DW_MACRO_GNU_transparent_include.
When working with the libelf library, both elf32_xlatetomd and elf64_xlatetomd now work for cross-endian ELF note data.
The elf_getshdr() function provided by the libelf library has been corrected to work consistently on non-mmapped ELF files after making the elf_cntl(ELF_C_FDREAD) function call.
The libelf library now supports ar archives with a 64-bit symbol table.
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The eu-readelf command is now able to display the contents of the .debug_macro section.
The eu-readelf command now correctly recognizes the DW_OP_GNU_parameter_ref DWARF
GNU extension opcode in location expressions.
A.4.2. Changes Since Red Hat Enterprise Linux 6.4
The following features have been added since the release of elfutils included in Red Hat Enterprise
Linux 6.4:
The libdw library now handles compressed debuginfo sections. The dwarf_highpc() function now handles the DWARF 4 DW_AT_high_pc constant form.
The eu-elflint utility now accepts executables produced by the gold linker.
The eu-nm utility now supports C++ demangling.
The eu-ar utility now supports a new modifier D for deterministic output with no UID, GID, or mtime info. The U modifier is the inverse.
The eu-readelf utility can now print SDT ELF notes (SystemTap probes) and the .gdb_index
GDB section. It can now also print DW_OP_GNU_entry_value and DW_AT_GNU_call_site families of DIE attributes.
The eu-strip utility now recognizes a new command line option, --reloc-debug-sections.
A.4.3. Changes Since Red Hat Enterprise Linux 5.9
In addition to the above changes, the following features have been added since the release of elfutils included in Red Hat Enterprise Linux 5.9:
DWARF 4 is now supported. As well, support for DW_OP_GNU_implicit_pointer and
ST B_GNU_UNIQUE has been added.
The libdwfl library now supports automatic decompression of files compressed with gzip, bzip2 and lzma, and of Linux kernel images made with gzip, bzip2 or lzma. Files named with compression suffixes are searched for Linux kernel images. Core file support was improved. Support has been added for decoding DWARF CFI into location description form. Support has been added for some new DWARF 3 expression operations, which were previously omitted. A new function,
dwfl_dwarf_line(), has been added.
The eu-elfcmp utility now supports a new command line option --ignore-build-id to ignore differing build ID bits. The new option --verbose (or -l for short) prints all differences.
The eu-strip utility now recognizes a new command line option --strip-sections to remove section headers entirely.
The libdw library now has new functions dwarf_next_unit(), dwarf_offdie_types(),
dwarf_lineisa(), dwarf_linediscrim inator(), dwarf_lineop_index(),
dwarf_getlocation_im plicit_pointer(), and dwarf_aggregate_size().
The eu-addr2line utility now recognizes a new command line option --flags (or -F for short) to print more DWARF line information details.
The libelf library now supports using more than 65536 program headers in a file. In addition, a new function elf_getphdrnum() has been added.
The eu-addr2line utility now accepts the --section=name option (or -j name for short) in the interests of binutils compatibility.
libcpu Intel SSE4 disassembler support has been added.
The eu-readelf utility now implements call frame information and exception handling dumping.
The -e command line option has been added; this is enabled implicitly by -a.
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A.5. Changes in dwz
Red Hat Developer Toolset 2.0 is distributed with dwz 0.11, which provides a number of bug fixes and enhancements over the version included in Red Hat Developer Toolset 1.1. Below is a comprehensive list of changes in this release.
A.5.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of dwz included in Red Hat Developer
Toolset 1.1:
The DW_FORM_data4, DW_FORM_data8, and DW_AT_high_pc attributes have been optimized.
The dwz utility now allocates more memory when recomputing abbreviations and no longer terminates unexpectedly.
The dwz utility no longer crashes when processing debugging information that contains several copies of the same Debugging Information Entry (DIE) within the same compilation unit.
The dwz utility no longer writes an incorrect DW_FORM code for a compilation unit version.
The dwz utility now supports version 8 of the .gdb_index section.
A.6. Changes in GDB
Red Hat Developer Toolset 2.0 is distributed with GDB 7.6, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in
Red Hat Developer Toolset 1.1. Below is a comprehensive list of new features in this release.
A.6.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of GDB included in Red Hat Developer
Toolset 1.1:
Target record has been renamed to record-full. Consequently, you can now use the record
full command to record or replay an execution log. In addition, the following commands have been renamed:
The set record insn-number-max and show record insn-number-max commands have been renamed to set record full insn-number-max and show record full
insn-num ber-m ax.
The set record memory-query and show record memory-query commands have been renamed to set record full memory-query and show record full memory-query.
The set record stop-at-limit and show record stop-at-limit commands have been renamed to set record full stop-at-limit and show record full stop-at-
lim it.
A new record target, record-btrace, has been added. This target uses hardware support to record the control flow of a process and can be enabled by using the record btrace command.
This record target does not support replaying the execution.
Important
The record-btrace target is only available on Intel Atom processors and requires the
Linux kernel in version 2.6.32 or later.
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New record instruction-history and record function-call-history commands have been added. These commands allow you to view information about an execution log without having to replay it. The record instruction-history command displays the execution history at instruction granularity and the record function-call-history displays the execution history at function granularity. The commands are only supported by the record btrace command.
A new command line option, -nh, has been added. This option allows you to disable automatic loading of the ~/.gdbinit file without disabling other initialization files.
The -epoch command line option has been removed. This option was used by GDB mode in Epoch, a deprecated clone of the Emacs text editor.
The ptype and whatis commands have been updated to accept an argument to control the type formatting.
The info proc command has been updated to work on some core files.
The cd command has been enhanced and no longer requires a directory path as its first argument.
When executed with no arguments, the command now changes to the home directory.
GDB now uses GNU v3 ABI as the default C++ ABI. This has been the default option for GCC since
November 2000.
The info tracepoints command has been enhanced to display installed on target or
not installed on target for each non-pending location of a tracepoint.
A new command, fo, has been added. This commands serves as a shorter variant of the forward-
search command.
A new command, catch signal, has been added. This command can be used to catch signals by their names and is similar to the handle command, but also allows you to attach additional conditions or commands.
A new command, maint info bfds, has been added. This command can be used to list all binary files (BFDs) opened by GDB.
Two new commands, python-interactive [command] and its shorter variant pi [command], have been added. These commands allow you to start an interactive Python prompt or evaluate a
Python command and print the results to standard output.
A new command, py [command], has been added. This command serves as a shorter variant of the
python [command] command.
New enable type-printer [name...] and disable type-printer [name...] commands have been added. These commands allow you to enable or disable type printers.
New set print type methods on|off and show print type methods commands have been added. These commands allow you to control whether method declarations are displayed by the ptype command. This functionality is enabled by default.
New set print type typedefs on|off and show print type typedefs commands have been added. These commands allow you to control whether typedef definitions are displayed by the ptype command. This functionality is enabled by default.
New set filename-display basename|relative|absolute and show filename-
display commands have been added. These commands allow you to control the way in which file names are displayed: the basename option displays only the base name of a file name, relative displays a path relative to the compilation directory, and absolute displays an absolute path to the file. The default option is relative to preserve the previous behavior.
New set trace-buffer-size and show trace-buffer-size commands have been added.
These commands allow you to control the size of the trace buffer for a target.
New set remote trace-buffer-size-packet auto|on|off and show remote trace-
buffer-size-packet commands have been added. These commands allow you to control the
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New set debug notification and show debug notification commands have been added. These commands allow you to control whether to display debugging information for asynchronous remote notification. This functionality is disabled by default.
New convenience functions $_memeq(buf1, buf2, length), $_streq(str1, str2),
$_strlen(str), and $_regex(str, regex) have been added.
The following changes have been made to the Python scripting support since the release of GDB included in Red Hat Developer Toolset 1.1:
Users can now create vectors by using the gdb.Type.vector() method.
The atexit.register() method is now supported.
Users can now pretty-print types by using the Python API.
In addition to Python 2.4 and later, GDB now also supports Python 3.
A new class, gdb.Architecture, has been added. This class exposes the internal representation of the architecture in the Python API.
A new method, Frame.architecture, has been added. This method can be used to return the
gdb.Architecture object corresponding to the frame's architecture.
Frame filters and frame decorators have been added.
The following MI changes have been made since the release of GDB included in Red Hat Developer
Toolset 1.1:
A new async record, =cmd-param-changed, has been added. This async record reports that a command parameter has changed.
A new async record, =traceframe-changed, has been added. This async record reports that a trace frame has been changed by using the tfind command.
New async records =tsv-created, =tsv-deleted, and =tsv-modified have been added.
These async records report that a trace state variable has been created, deleted, or modified.
New async records =record-started and =record-stopped have been added. These async records report that a process record has been started or stopped.
A new async record, =memory-changed, has been added. This async record reports that the memory has changed.
When the source is requested, the -data-disassemble command now includes a new fullname field containing an absolute path to the source file name.
A new optional parameter, COUNT, has been added to the -data-write-memory-bytes command. This parameter can be used to allow pattern filling of memory areas.
New commands -catch-load and -catch-unload have been added. These commands can be used to intercept shared library load/unload events.
The response to breakpoint commands and breakpoint async records now includes a new
installed field. This field reports the current state of each non-pending tracepoint location: when the tracepoint is installed, the value of this field is y, otherwise the value is n.
The output of the -trace-status command now includes a new trace-file field. This field is only present when examining a trace file and contains the name of this file.
The fullname filed is now always present along with the file field. This field is included even if
GDB cannot find the file.
A number of new remote packets have been added since the release of GDB included in Red Hat
Developer Toolset 1.1. See Table A.3, “New Remote Packets”
for a complete list.
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Table A.3. New Remote Packets
Remote Packet
QT Buffer:size
Qbtrace:bts
Qbtrace:off qXfer:btrace:read qXfer:libraries-
svr4 :read's annex
Description
Sets the size of the trace buffer. The remote stub reports support for this packet to the qSupported query.
Enables branch tracing based on Branch Trace Store (BTS) for the current thread. The remote stub reports support for this packet to the qSupported query.
Disables branch tracing for the current thread. The remote stub reports support for this packet to the qSupported query.
Reads the traced branches for the current thread. The remote stub reports support for this packet to the qSupported query.
The previously unused annex of the qXfer:libraries-
svr4 :read packet is now used to support passing of an argument list. The remote stub reports support for this argument list to the qSupported query.
The defined arguments are start and prev. These arguments are used to reduce work necessary for updating the library list and significantly speed up the process.
A.6.2. Changes Since Red Hat Enterprise Linux 6.4
The features below have been added since the release of GDB included in Red Hat Enterprise Linux
6.4.
New Features
Support for linespecs has been improved (in particular, a more consistent handling of ambiguous linespecs, some support for labels in the program's source, and FILE:LINE support now extends to further linespecs types). Breakpoints are now set on all matching locations in all inferiors and will be updated according to changes in the inferior.
New inferior control commands skip function and skip file have been added. These commands can be uses to skip certain functions and files when stepping.
The info threads command now displays the thread name as set by prctl or
pthread_setnam e_np. In addition, new commands thread nam e and thread find have been added. The thread name command accepts a name as an argument and can be used to set the name of the current thread. The thread find command accepts a regular expression and allows the user to find threads that match it.
GDB now provides support for reading and writing a new .gdb_index section. The command gdb-
add-index can be used to add .gdb_index to a file, which allows GDB to load symbols from that file faster. Note that this feature is already present in Red Hat Enterprise Linux 6.1 and later.
The watch command has been adapted to accept -location as an optional argument.
Two new special values can now be used when specifying the current search path for
libthread_db: $sdir represents the default system locations of shared libraries, and $pdir stands for the directory with the libthread that is used by the application.
A new command info macros has been added. This command accepts linespec as an optional argument and can be used to display the definitions of macros at that linespec location. Note that in order to do this, the debugged program must be compiled with the -g3 command line option to have
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A new command alias has been added. This command can be used to create an alias of an existing command.
The info macro command now accepts -all and -- as valid options.
To display a function parameter's entry value (that is, the value at the time of function entry), the suffix @entry can be added to the parameter. GDB now displays @entry values in backtraces, if available.
New set print entry-values and show print entry-values commands have been added.
The set print entry-values command accepts both, compact, default, if-needed, no,
only, and preferred as valid arguments and can be used to enable printing of function arguments at function entry. The show print entry-values command can be used to determine whether this feature is enabled.
New set debug entry-values and show debug entry-values commands have been added.
The set debug entry-values command can be used to enable printing of debugging information for determining frame argument values at function entry and virtual tail call frames.
!command has been added as an alias of shell command.
The watch command now accepts mask mask_value as an argument. This can be used to create masked watchpoints.
New set extended-prompt and show extended-prompt commands have been added. The
set extended-prom pt command enables support for a defined set of escape sequences that can be used to display various information. The show extended-prompt command can be used to determine whether the extended prompt is enabled.
New set basenames-may-differ and show basenames-may-differ commands have been added. The set basenames-may-differ command enables support for source files with multiple base names. The show basenames-may-differ command can be used to determine whether this support is enabled. The default option is off to allow faster GDB operations.
A new command line option -ix (or --init-command) has been added. This option acts like -x (or
--com m and), but is executed before loading the debugged program.
A new command line option -iex (or --init-eval-command) has been added. This option acts like -ex (or --eval-command), but is executed before loading the debugged program.
The info os command has been changed and can now display information on several objects managed by the operating system, in particular:
The info os procgroups command lists process groups.
The info os files command lists file descriptors.
The info os sockets command lists internet-domain sockets.
The info os shm command lists shared-memory regions.
The info os semaphores command lists semaphores.
The info os msg command lists message queues.
The info os modules command lists loaded kernel modules.
GDB now has support for Static Defined Tracing (SDT) probes. Currently, the only implemented back end is for SystemTap probes (the sys/sdt.h header file). You can set a breakpoint by using the new -probe, -pstap, or -probe-stap options, and inspect the probe arguments by using the new
$_probe_arg family of convenience variables.
The symbol-reloading option has been deleted.
gdbserver now supports STDIO connections, for example:
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Changes in Version 2.0
(gdb) target remote | ssh myhost gdbserver - hello
GDB is now able to print flag enums. In a flag enum, all enumerator values have no bits in common when pairwise AND-ed. When GDB prints a value whose type is a flag enum, GDB shows all the constants; for example, for enum E { ONE = 1, TWO = 2}:
(gdb) print (enum E) 3
$1 = (ONE | TWO)
The file name part of a linespec now matches trailing components of a source file name. For example,
break gcc/expr.c:1000 now sets a breakpoint in the build/gcc/expr.c file, but not in
build/libcpp/expr.c.
The info proc and generate-core-file commands now work on remote targets connected to
gdbserver.
The command info catch has been removed.
The Ada-specific catch exception and catch assert commands now accept conditions at the end of the command.
The info static-tracepoint-marker command now works on native targets with an inprocess agent.
GDB can now set breakpoints on inline functions.
The .gdb_index section has been updated to include symbols for inline functions. By default, GDB now ignores older .gdb_index sections until their .gdb_index sections can be recreated. The new command set use-deprecated-index-sections on causes GDB to use any older
.gdb_index sections it finds. If this option is set, the ability to set breakpoints on inline functions is lost in symbol files with older .gdb_index sections.
The .gdb_index section has also been updated to record more information about each symbol.
GDB now provides Ada support for GDB/MI Variable Objects.
GDB now supports breakpoint always-inserted mode in the record target.
gdbserver now supports evaluation of breakpoint conditions. Note that you can instruct GDB to send the breakpoint conditions in bytecode form, but gdbserver only reports the breakpoint trigger to GDB when its condition evaluates to true.
The z0/z1 breakpoint insertion packets have been extended to carry a list of conditional expressions over to the remote stub depending on the condition evaluation mode. You can use the
set rem ote conditional-breakpoints-packet command to control the use of this extension.
A new RSP packet QProgramSignals can be used to specify the signals the remote stub can pass to the debugged program without GDB involvement.
A new command -info-os has been added as the MI equivalent of info os.
Output logs, such as set logging and related, now include MI output.
New set use-deprecated-index-sections on|off and show use-deprecated-index-
sections on|off commands have been added. These commands allow you to control the use of deprecated .gdb_index sections.
New catch load and catch unload commands have been added. These commands allow you to stop execution of a debugged program when a shared library is loaded or unloaded.
A new command enable count has been added. This command allows you to auto-disable a breakpoint after several hits.
A new command info vtbl has been added. This command allows you to show the virtual method tables for C++ and Java objects.
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A new command explore has been added. It supports two subcommands explore value and
explore type, and allows you to recursively explore values and types of expressions. Note that this command is only available with Python-enabled GDB.
A new command dprintf location,format,args... has been added. This command allows you to create a dynamic printf-type breakpoint, which performs a printf-like operation and then resumes program execution.
New set print symbol and show print symbol commands have been added. These commands allow you to control whether GDB attempts to display the symbol, if any, that corresponds to addresses it prints. This functionality is enabled by default, but you can restore the previous behavior by running the set print symbol off command.
New set breakpoint condition-evaluation and show breakpoint condition-
evaluation commands have been added. These commands allow you to control whether breakpoint conditions are evaluated by GDB (the host option), or by gdbserver (the target option). The default option, auto, chooses the most efficient available mode.
New set dprintf-style gdb|call|agent and show dprintf-style commands have been added. These commands allow you to control the way in which a dynamic printf is performed: the
gdb option requests a GDB printf command, call causes dprintf to call a function in the inferior, and agent requests that the target agent such as gdbserver does the printing.
New set dprintf-function expression, show dprintf-function, set dprintf-
channel expression, and show dprintf-channel commands have been added. These commands allow you to set the function and optional first argument to the call when using the call style of dynamic printf.
New set disconnected-dprintf on|off and show disconnected-dprintf commands have been added. These commands allow you to control whether agent-style dynamic printfs continue to be in effect after GDB disconnects.
The following changes have been made to the C++ language support since the release of the GNU
Debugger included in Red Hat Enterprise Linux 6.2:
When debugging a template instantiation, parameters of the template are now put in scope.
The following changes have been made to the Python scripting support since the release of the GNU
Debugger included in Red Hat Enterprise Linux 6.2:
The register_pretty_printer function in module gdb.printing now takes an optional
replace argument.
The maint set python print-stack on|off command has been deprecated and will be deleted in GDB 7.5. The new command set python print-stack none|full|message has replaced it.
A prompt substitution hook (prompt_hook) is now available to the Python API.
A new Python module gdb.prompt has been added to the GDB Python modules library.
Python commands and convenience-functions located in
data_directory/python/gdb/com m and/ and data_directory/python/gdb/function/ are now automatically loaded on GDB start-up.
Blocks now provide four new attributes: global_block, static_block, is_static, and
is_global.
The gdb.breakpoint function has been deprecated in favor of gdb.breakpoints.
A new class gdb.FinishBreakpoint is provided.
Type objects for struct and union types now allow access to the fields using standard Python
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Changes in Version 2.0 dictionary (mapping) methods.
A new event gdb.new_objfile has been added.
A new function deep_items has been added to the gdb.types module.
The function gdb.Write now accepts an optional keyword stream.
Parameters can now be sub-classed in Python, which allows for implementation of the get_set_doc and get_show_doc functions.
Symbols, Symbol Table, Symbol Table and Line, Object Files, Inferior, Inferior Thread, Blocks, and
Block Iterator APIs now have an is_valid method.
Breakpoints can now be sub-classed in Python, which allows for implementation of the stop function that is executed each time the inferior reaches that breakpoint.
A new function gdb.lookup_global_symbol has been added. This function can be used to look up a global symbol.
GDB values in Python are now callable if the value represents a function.
A new module gdb.types has been added.
A new module gdb.printing has been added.
New commands info pretty-printers, enable pretty-printer, and disable pretty-
printer have been added.
A new gdb.parameter("directories") function call is now available.
A new function gdb.newest_frame has been added. This function can be used to return the newest frame in the selected thread.
The gdb.InferiorThread class now supports a new name attribute.
Support for inferior events has been added. Python scripts can now add observers in order to be notified of events occurring in the process being debugged.
GDB commands implemented in Python can now be put in the gdb.COMMAND_USER command class.
The maint set python print-stack on|off command has been removed and replaced by
set python print-stack.
A new class gdb.printing.FlagEnumerationPrinter has been added. This class can be used to apply flag enum-style pretty-printing to enums.
The gdb.lookup_symbol function now works correctly when there is no current frame.
The gdb.Symbol object now has an additional attribute line. This attribute holds the line number in the source at which the symbol was defined.
The gdb.Symbol object now has an additional attribute needs_frame, and a new method value.
The needs_frame attribute indicates whether the symbol requires a frame to compute its value, and the value method computes the symbol's value.
The gdb.Value object now has a new method referenced_value. This method can be used to dereference a pointer as well as C++ reference values.
The gdb.Symtab object now has two new methods, global_block and static_block. These methods return the global and static blocks (as gdb.Block objects) of the underlying symbol table respectively.
A new method gdb.find_pc_line returns the gdb.Symtab_and_line object associated with a
PC value.
The gdb.Symtab_and_line object now has an additional attribute last. This attribute holds the end of the address range occupied by the code for the current source line.
Compatibility Changes
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A new command info auto-load has been added and can be used to display the status of various automatically loaded files. The info auto-load gdb-scripts command lists automatically loaded canned sequences of commands, info auto-load python-scripts displays the status of automatically loaded Python scripts, info auto-load local-gdbinit displays whether a local .gdbinit file in the current working directory is loaded, and info auto-
load libthread-db displays whether the inferior-specific thread debugging shared library is loaded.
New commands set auto-load and show auto-load have been added and can be used to control automatic loading of files:
The set auto-load gdb-scripts and show auto-load gdb-scripts commands control automatic loading of GDB scripts.
The set auto-load python-scripts and show auto-load python-scripts commands control automatic loading of Python scripts.
The set auto-load local-gdbinit and show auto-load local-gdbinit commands control automatic loading of .gdbinit from the current working directory.
The set auto-load libthread-db and show auto-load libthread-db commands control automatic loading of inferior-specific libthread_db.
The set auto-load scripts-directory and show auto-load scripts-directory commands control the list of directories from which to automatically load GDB and Python scripts.
The set auto-load safe-path and show auto-load safe-path commands control the list of directories from which it is safe to automatically load all previously mentioned items.
The set debug auto-load and show debug auto-load commands control displaying of debugging information for all previously mentioned items.
The set auto-load off command can be used to disable automatic loading globally. You can also use show auto-load with no subcommand to display current settings of all previously mentioned items.
The maint set python auto-load on|off command has been replaced with set auto-
load python-scripts on|off.
The maintenance print section-scripts command has been renamed to info auto-
load python-scripts [pattern] and is no longer classified as a maintenance-only command.
Support for the Guile extension language has been removed.
The GNU Debugger has been adapted to follow GCC's rules on accessing volatile objects when reading or writing target state during expression evaluation.
A.6.3. Changes Since Red Hat Enterprise Linux 5.9
In addition to the above changes, the features below have been added since the release of GDB included in Red Hat Enterprise Linux 5.9.
New Features
For remote targets, debugging of shared libraries is now supported by default.
New commands set observer and show observer have been added. The set observer command accepts on or off as an argument and can be used to allow or disallow the GNU
Debugger to affect the execution of the debugged program. Use the show observer command to determine whether observer mode is enabled.
A new convenience variable $_thread has been added. This variable stores the number of the current thread.
The source command now accepts -s as a valid option. This option can be used to search for the
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Changes in Version 2.0 script in the source search path regardless of the path in the file name.
Support for tracepoints, including fast and static tracepoints, has been added to gdbserver.
The --batch command line option has been adapted to disable pagination and queries.
Direct support for the reading and writing byte, word, and double-word x86 general purpose registers such as $al has been added.
The commands command now accepts a range of breakpoints as an argument.
The rbreak command now accepts a file name as part of its argument. This can be used to limit the functions selected by the supplied regular expression to those that are defined in the specified file.
Support for multi-program (sometimes referred to as multi-executable or multi-exec) debugging has been added. In particular, the GNU Debugger now supports the following commands:
The add-inferior command can be used to add a new inferior.
The clone-inferior command can be used to create a copy of an inferior with the same executable loaded.
The remove-inferior command accepts an inferior ID as an argument and can be used to remove an inferior.
Support for trace state variables has been added. In particular, the GNU Debugger now supports the following commands:
The tvariable $variable_name [= expression] command can be used to define or modify a trace state variable.
The info tvariables command can be used to display a list of currently defined trace state variables and their values.
The delete tvariable $variable_name... command can be used to delete one or more trace state variables.
A new ftrace has been added. This command accepts a function name, a line number, or an address as an argument, and can be used to define a fast tracepoint at that location.
Support for disconnected tracing, trace files, and circular trace buffer has been added.
A new teval command has been added. This command accepts one or more expressions to evaluate at a tracepoint.
The GNU Debugger has been adapted to parse the 0b prefix of binary numbers exactly the same way as the GNU Compiler Collection.
The GNU Debugger now supports the following commands for process record and replay:
New commands set record memory and show record memory have been added. The
set record m em ory command accepts on or off as an argument and can be used to enable or disable stopping the inferior when a memory change of the next instruction cannot be recorded. Use the show record memory-query command to determine whether this feature is enabled.
A new command record save has been added. This command accepts a file name as an argument and can be used to save the execution log to a file.
A new command record restore has been added. This command accepts a file name as an argument and can be used to restore the execution log from a file.
A new command eval has been added. This command accepts a format string followed by one or more arguments, transforms it to a command, and then executes it.
A new command save breakpoints has been added. This command accepts a file name as an argument and can be used to store all currently defined breakpoints to a file. To restore the saved breakpoints from this file, use the source command.
New commands set may-write-registers, set may-write-memory, set may-insert-
breakpoints, set m ay-insert-tracepoints, set m ay-insert-fast-tracepoints, and
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set m ay-interrupt have been added. All of these commands accept either on or off as an argument, and can be used to set individual permissions for the target.
A new command main info program-spaces has been added. This command can be used to display information about currently loaded program spaces.
New commands set remote interrupt-sequence and show remote interrupt-
sequence have been added. The set rem ote interrupt-sequence command accepts Ctrl-
C, BREAK, and BREAK-g as valid arguments, and can be used to specify which interrupt sequence to send to the remote target in order to interrupt its execution. Use the show remote interrupt-
sequence to determine the current setting.
New commands set remote interrupt-on-connect and show remote interrupt-on-
connect have been added. The set rem ote interrupt-on-connect accepts either on or
off as an argument, and can be used to enable sending an interrupt sequence to the remote target when the GNU Debugger connects to it. Use the show remote interrupt-on-connect command to determine whether this feature is enabled.
The set remotebreak and show remotebreak commands have been deprecated and users are advised to use set remote interrupt-sequence and show remote interrupt-
sequence instead.
The disassemble command has been adapted to accept two arguments in the form of
start,+length.
The source command can now be used to read commands from Python scripts.
The following changes have been made to the C++ language support since the release of the GNU
Debugger included in Red Hat Enterprise Linux 5.8:
Argument-dependent lookup (ADL) now directs function search to the namespaces of its arguments regardless of whether the namespace has been imported.
In addition to member operators, the GNU Debugger can now look up operators that are: defined in the global scope, defined in a namespace and imported via the using directive, implicitly imported from an anonymous namespace, or the argument-dependent lookup (ADL operators.
Support for printing of static const class members that are initialized in the class definition has been enhanced.
Support for importing of namespaces has been added.
The C++ expression parser has been adapted to handle the cast operators static_cast<>,
dynam ic_cast<>, const_cast<>, and reinterpret_cast<>.
The following changes have been made to the Python scripting support since the release of the GNU
Debugger in Red Hat Enterprise Linux 5.8:
The GNU Debugger is now installed with a new directory located at /opt/rh/devtoolset-
2/root/usr/share/gdb/python/. This directory serves as a standard location for Python scripts written for GDB.
The Python API has been adapted to provide access to symbols, symbol tables, program spaces, breakpoints, inferiors, threads, and frame's code blocks. Users are now also allowed to create custom GDB parameters from the API and manipulate them by using the set and show commands.
New functions gdb.target_charset, gdb.target_wide_charset, gdb.progspaces,
gdb.current_progspace, and gdb.string_to_argv have been added.
A new exception gdb.GdbError has been added.
132
Changes in Version 2.0
The GNU Debugger now searches pretty-printers in the current program space.
The GNU Debugger can now enable or disable pretty-printers individually.
The GNU Debugger has been adapted to look for names of Python scripts to automatically load in a special section named .debug_gdb_scripts.
A.7. Changes in strace
Red Hat Developer Toolset 2.0 is distributed with strace 4 .7, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features in this release.
A.7.1. Changes Since Red Hat Enterprise Linux 6.4 and 5.9
The following features have been added since the release of strace in Red Hat Enterprise Linux 6.4 and
5.9:
A new command line option, -y, has been added. This option can be used to print file descriptor paths.
A new command line option, -P, has been added. This option can be used to filter system calls based on the file descriptor paths.
A new command line option, -I, has been added. This option can be used to control how interactive
strace is.
A new command line utility, strace-log-merge, has been added. This utility can be used to merge timestamped strace output into a single file.
The strace utility now uses optimized interfaces to extract data from the traced process for better performance.
The strace utility now provides improved support for decoding of arguments for various system calls. In addition, a number of new system calls are supported.
A.8. Changes in SystemTap
Red Hat Developer Toolset 2.0 is distributed with SystemTap 2.1, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer Toolset 1.1. Below is a comprehensive list of new features in this release.
A.8.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of SystemTap included in Red Hat Developer
Toolset 1.1:
SystemTap has been updated to provide experimental support for Dyninst-based probing in the user space. Users can now execute the stap utility with the --dyninst command line option to instrument their own programs without the need to acquire root privileges.
SystemTap is now distributed with a number of manual pages that provide a detailed explanation of common errors:
The error::buildid(7stap) manual page documents build-id verification failures.
The error::dwarf(7stap) manual page documents common DWARF debuginfo quality problems.
The error::fault(7stap) manual page documents memory access faults.
The error::inode-uprobes(7stap) manual page documents current limitations of inodeuprobes.
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Red Hat Developer Toolset 2.x User Guide
The error::pass1(7stap) manual page documents pass 1 (parsing) errors.
The error::pass2(7stap) manual page documents pass 2 (elaboration) errors.
The error::pass3(7stap) manual page documents pass 3 (translation) errors.
The error::pass4(7stap) manual page documents pass 4 (compilation) errors.
The error::pass5(7stap) manual page documents pass 5 (execution) errors.
The error::process-tracking(7stap) manual page documents user-space process tracking errors.
The error::reporting(7stap) manual page documents how to report SystemTap bugs.
The scripting language used by SystemTap now supports the =~ operator. Users can use this operator to match regular expressions.
The preprocessor used by the stap utility now supports an experimental macro facility. Users can use the following construct to define new macros:
@define name(parameter...) %( body %)
Refer to the PREPROCESSOR MACROS section of the stap(1) manual page for more information on how to use this feature.
The backtrace-related tapset functions have been improved and standardized.
A.9. Changes in OProfile
Red Hat Developer Toolset 2.0 is distributed with OProfile 0.9.8, which provides a number of a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer Toolset 1.1. Below is a comprehensive list of new features in this release.
A.9.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of OProfile included in Red Hat Developer
Toolset 1.1:
A new command line utility, operf, has been added. This utility can be executed by a non-root user and can be used to collect profiling data.
Important
The operf utility relies on a kernel feature that is currently not available in Red Hat
Enterprise Linux 5. Consequently, this utility only works and is supported on Red Hat
Enterprise Linux 6.
OProfile now supports Intel processors code-named Ivy Bridge.
A.9.2. Changes Since Red Hat Enterprise Linux 5.9
The following features have been added since the release of OProfile included in Red Hat Enterprise
Linux 5.9:
OProfile now supports AMD family11h, family12h, family14h, and AMD family15h processors.
Generation of XML output has been corrected.
Handling of the --session-dir command line option has been improved and a possible buffer
134
Changes in Version 2.0 overflow in the XML generator has been fixed.
A.10. Changes in Valgrind
Red Hat Developer Toolset 2.0 is distributed with Valgrind 3.8.1, which provides a number of bug fixes over the version included in Red Hat Developer Toolset 1.1. Below is a comprehensive list of changes in this release.
A.10.1. Changes Since Red Hat Developer Toolset 1.1
The following features have been added since the release of Valgrind included in Red Hat Developer
Toolset 1.1:
The DWARF debug information for Valgrind is now distributed in a separate package, devtoolset-2-
valgrind-debuginfo.
The SGCHECK OPTIONS section of the valgrind(1) manual page has been corrected and no longer includes the BBV options. As well, the BBV options are now listed in a separate section.
A.10.2. Changes Since Red Hat Enterprise Linux 5.9
In addition to the above changes, the following features have been added since the release of Valgrind
3.5.0 included in Red Hat Enterprise Linux 5.9:
When running in 64-bit mode, Valgrind now supports the SSE4.2 instruction set with the exception of
SSE4.2 AES instructions. In 32-bit mode, Valgrind only provides support up to and including the
SSSE3 instruction set.
A new processing script cg_diff has been added to Cachegrind. This processing script can find the difference between two profiles, and can therefore be used to evaluate the performance effects of a change in a program.
The behavior of the cg_annotate's rarely-used --threshold option has been changed.
Callgrind now supports branch prediction simulation and can optionally count the number of executed global bus events. Note that in order to use this functionality for a better approximation of a
“Cycle Estimation” as a derived event, you must manually update the event formula in KCachegrind.
To accommodate machines with three levels of caches, both Cachegrind and Callgrind now refer to the LL (last-level) cache rather than the L2 cache. When Cachegrind or Callgrind auto-detects the cache configuration of such a machine, it now runs the simulation as if the L2 cache is not present. Consequently, the results are less likely to match the true result for the machine and should not be considered authoritative, but provide a general idea about a program's locality.
A new command line option --pages-as-heap has been added to Massif. When this option is enabled, Massif tracks memory allocations at the level of memory pages (as mapped by mmap, brk and similar functions) instead of tracking allocations at the level of heap blocks (as allocated with
m alloc, new, or new[]). Each mapped page is treated as its own block. Interpreting the page-level output is harder than the heap-level output, but allows you to account for every byte of memory used by a program. By default, the --pages-as-heap option is disabled.
New command line options --free-is-write and --trace-alloc have been added to DRD.
The --free-is-write option allows you to detect reading from already freed memory, the --
trace-alloc can be used to trace of all memory allocations and deallocations.
A number of new allocations have been added to DRD. As well, you can now annotate custom barrier implementations and benign races on static variables.
DRD's happens before and happens after annotations have been enhanced and can be used to annotate, for example, a smart pointer implementation.
Helgrind's annotation set has been significantly improved to provide a general set of annotations to
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Red Hat Developer Toolset 2.x User Guide describe locks, semaphores, barriers, and condition variables. In addition, Helgrind now supports annotations to describe thread-safe reference counted heap objects.
A new command line option --show-possibly-lost has been added to Memcheck. By default this option is enabled and causes the leak detector to show possibly-lost blocks.
A new experimental heap profiler, DHAT (Dynamic Heap Analysis Tool), has been added. DHAT keeps track of allocated heap blocks, and also inspects every memory reference to see which block
(if any) is being accessed. This gives a lot of insight into block lifetimes, utilization, turnover, liveness, and the location of hot and cold fields. You can use DHAT to do hot-field profiling.
Support for unfriendly self-modifying code has been improved, and the extra overhead incurred by --
sm c-check=all has been reduced by approximately a factor of 5 as compared with the previous version of Valgrind.
A new command line option --fullpath-after has been added. This option can be used to display directory names for source files in error messages, and is combined with a flexible mechanism for specifying which parts of the paths should be shown.
A new command line option --require-text-symbol has been added. This option stops the execution if a specified symbol is not found in a given shared object when loaded into the process.
As a result, working with function intercepting and wrapping is now safer and more reliable.
Valgrind now implements more reliable stack unwinding on amd64-linux, particularly in the presence of function wrappers, and with gcc-4.5 compiled code.
Valgrind now implements modest scalability (performance improvements) for very large, long-running applications.
Valgrind now provides improved support for analyzing programs that are running in Wine. Users can now include the valgrind/valgrind.h, valgrind/memcheck.h, and valgrind/drd.h header files in Windows programs that are compiled with MinGW or one of the Microsoft Visual
Studio compilers.
136
Revision History
Revision History
Revision 1.0-2 Tue 10 Sep 2013
Red Hat Developer Toolset 2.0 GA release of the User Guide.
Jaromír Hradílek
Revision 1.0-1 Tue 06 Aug 2013
Red Hat Developer Toolset 2.0 Beta-2 release of the User Guide.
Jaromír Hradílek
Revision 1.0-0 Tue 28 May 2013
Red Hat Developer Toolset 2.0 Beta-1 release of the User Guide.
Jaromír Hradílek
Index
A
ABI
-
compatibility, ABI Compatibility
addr2line
-
-
-
usage, Using Other Binary Tools
application binary interface (see ABI) ar
-
-
usage, Using Other Binary Tools
as (see GNU assembler) assembling (see GNU assembler)
B bfd
-
binutils
-
documentation, Additional Resources
-
-
installation, Installing binutils
-
-
usage, Using the GNU Assembler
-
version, About Red Hat Developer Toolset
C
C programming language
137
Red Hat Developer Toolset 2.x User Guide
-
compiling, Using the C Compiler
, Preparing a Program for Debugging
-
-
C++ programming language
-
compiling, Using the C++ Compiler
, Preparing a Program for Debugging
-
running, Running a C++ Program
-
C++11 (see GNU Compiler Collection) c++filt
-
-
usage, Using Other Binary Tools
C11 (see GNU Compiler Collection)
Cachegrind
-
-
Callgrind
-
-
compatibility
GNU Compiler Collection, Language Compatibility
Compatibility , Fortran 2008 Compatibility , Fortran 77 Compatibility , ABI Compatibility ,
,
-
Red Hat Developer Toolset, Compatibility
compiling (see GNU Compiler Collection)
Customer Portal
-
Connect menu, The Connect Menu
-
-
overview, Accessing the Customer Portal
-
D debugging (see GNU Debugger)
Developer Toolset (see Red Hat Developer Toolset) documentation
- Red Hat Product Documentation,
Accessing Red Hat Product Documentation
138
DRD
-
-
dwp
-
-
usage, Using Other Binary Tools
dwz
-
documentation, Additional Resources
-
-
-
-
version, About Red Hat Developer Toolset
Dyninst
-
documentation, Additional Resources
-
installation, Installing Dyninst
-
-
-
version, About Red Hat Developer Toolset
E
Eclipse
-
configuration, Using the Red Hat Enterprise Linux Toolchain
-
documentation, Additional Resources
-
installation, Installing Eclipse
-
-
-
version, About Red Hat Developer Toolset
elfedit
-
-
-
usage, Using Other Binary Tools
elfutils
-
documentation, Additional Resources
-
installation, Installing elfutils
-
-
-
version, About Red Hat Developer Toolset
eu-addr2line
-
features, Changes Since Red Hat Enterprise Linux 5.9
-
-
Revision History
139
Red Hat Developer Toolset 2.x User Guide
eu-ar
-
features, Changes Since Red Hat Enterprise Linux 6.4
-
-
eu-elfcmp
-
features, Changes Since Red Hat Enterprise Linux 5.9
-
-
eu-elflint
-
features, Changes Since Red Hat Enterprise Linux 6.4
-
-
eu-findtextrel
-
-
eu-make-debug-archive
-
-
eu-nm
-
features, Changes Since Red Hat Enterprise Linux 6.4
-
-
eu-objdump
-
-
eu-ranlib
-
-
eu-readelf
- features, Changes Since Red Hat Enterprise Linux 6.4
-
-
14 0 eu-size
Revision History
-
-
eu-strings
-
-
eu-strip
- features, Changes Since Red Hat Enterprise Linux 6.4
-
-
eu-unstrip
-
-
F feedback
-
contact information for this manual, We Need Feedback
Fortran programming language
-
compiling, Using the Fortran Compiler
-
running, Running a Fortran Program
-
G g++ (see GNU Compiler Collection)
GAS (see GNU assembler)
GCC (see GNU Compiler Collection) gcc (see GNU Compiler Collection)
GDB (see GNU Debugger) gfortran (see GNU Compiler Collection)
Global Support Services
- contacting,
Contacting Global Support Services
GNU assembler
-
documentation, Additional Resources
-
installation, Installing binutils
-
-
usage, Using the GNU Assembler
14 1
Red Hat Developer Toolset 2.x User Guide
GNU Binutils (see binutils)
GNU Compiler Collection
-
-
-
compatibility, Language Compatibility
,
,
Fortran 2008 Compatibility , Fortran 77 Compatibility , ABI Compatibility
Compatibility , Other Compatibility
-
documentation, Additional Resources
-
,
,
-
Fortran support, GNU Fortran Compiler
installation, Installing the C Compiler
-
overview, GNU Compiler Collection (GCC)
-
,
Preparing a Program for Debugging
-
version, About Red Hat Developer Toolset
, GNU Compiler Collection (GCC)
GNU Debugger
-
documentation, Additional Resources
-
-
installation, Installing the GNU Debugger
-
-
preparation, Preparing a Program for Debugging
usage, Running the GNU Debugger
Execution , Displaying Current Values , Continuing Execution
-
version, About Red Hat Developer Toolset
GNU linker
-
documentation, Additional Resources
-
installation, Installing binutils
-
-
gprof
-
-
-
usage, Using Other Binary Tools
GSS (see Global Support Services)
H
Helgrind
-
-
14 2 help
-
accessing the Customer Portal, Accessing the Customer Portal
- getting help,
-
Global Support Services, Contacting Global Support Services
- Red Hat Product Documentation,
Accessing Red Hat Product Documentation
Revision History
L ld (see GNU linker) linking (see GNU linker)
M
Massif
-
-
Memcheck
-
-
memstomp
-
documentation, Additional Resources
-
installation, Installing memstomp
-
-
-
version, About Red Hat Developer Toolset
N nm
-
-
usage, Using Other Binary Tools
O objcopy
-
-
-
usage, Using Other Binary Tools
objdump
-
-
-
usage, Using Other Binary Tools
opannotate
14 3
R
14 4
Red Hat Developer Toolset 2.x User Guide
-
-
oparchive
-
-
opcontrol
-
-
opgprof
-
-
ophelp
-
-
opimport
-
-
opjitconv
-
-
opreport
-
-
OProfile
-
documentation, Additional Resources
-
installation, Installing OProfile
-
-
-
version, About Red Hat Developer Toolset
oprofiled
-
-
Revision History
ranlib
-
-
usage, Using Other Binary Tools
readelf
-
-
-
usage, Using Other Binary Tools
Red Hat Customer Portal (see Customer Portal)
Red Hat Developer Toolset
-
-
documentation, Additional Resources
,
Accessing Red Hat Product Documentation
-
-
installation, Installing Red Hat Developer Toolset
-
overview, About Red Hat Developer Toolset
-
subscription, Getting Access to Red Hat Developer Toolset
-
support, About Red Hat Developer Toolset
-
uninstallation, Uninstalling Red Hat Developer Toolset
-
update, Updating Red Hat Developer Toolset
Red Hat Enterprise Linux
-
documentation, Additional Resources
,
Accessing Red Hat Product Documentation
-
supported versions, Compatibility
Red Hat Subscription Management
-
subscription, Using Red Hat Subscription Management
RHN Classic
-
subscription, Using RHN Classic
S scl (see Software Collections) size
-
-
usage, Using Other Binary Tools
Software Collections
-
documentation, Additional Resources
,
Accessing Red Hat Product Documentation
-
overview, About Red Hat Developer Toolset
stap
-
-
, Using Dyninst with SystemTap
14 5
Red Hat Developer Toolset 2.x User Guide
stap-merge
-
-
stap-prep
-
-
stap-report
-
-
staprun
-
-
stapsh
-
-
strace
-
documentation, Additional Resources
-
installation, Installing strace
-
-
-
version, About Red Hat Developer Toolset
strings
-
-
usage, Using Other Binary Tools
strip
-
-
usage, Using Other Binary Tools
support
-
Red Hat Developer Toolset, About Red Hat Developer Toolset
14 6
SystemTap
-
documentation, Additional Resources
-
installation, Installing SystemTap
-
-
, Using Dyninst with SystemTap
-
version, About Red Hat Developer Toolset
V
Valgrind
-
documentation, Additional Resources
-
installation, Installing Valgrind
-
-
-
version, About Red Hat Developer Toolset
version
-
Revision History
14 7
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