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GNU Toolchain Update (glibc 2.36, binutils 2.38)

Summary

Update the Fedora 37 GNU Toolchain to glibc 2.36, binutils 2.38.

The set of core GNU Toolchain packages for Fedora 37 are as follows:

  • GNU C Compiler 12 (first released in Fedora 36)
    • Associated runtimes for C++ (libstdc++), Go (gccgo), OpenMP (gomp), Fortran (gfortran), D (phobos), Objective C/C++.
  • GNU Binary Utilities 2.38 (expected release in Fedora 37)
  • GNU C Library 2.36 (expected release in Fedora 37)
  • GNU Debugger 12 (immediately available in Fedora 35, 36, and 37)

The glibc 2.36 change will be tracked in this top-level GNU Toolchain system-wide update.

The binutils 2.38 change will be tracked in this top-level GNU Toolchain system-wide update.

Owner


Current status

  • Targeted release: Fedora Linux 37
  • Last updated: 2022-08-25
  • devel thread
  • Updated redhat-rpm-config: [] (TODO: Check if redhat-rpm-config needs updating for the new toolchain)
    • Are config.guess and config.sub up to date from upstream?
  • FESCo issue: #2831
  • Tracker bug: #2108675
  • Release notes tracker: #862

Detailed Description

The GNU Compiler Collection, GNU C Library, GNU Debugger, and GNU Binary Utilities make up the core part of the GNU Toolchain and it is useful for our users to transition these components as a complete implementation when making a new release of Fedora.


The GNU C Library version 2.36 is expected to be released in the beginning of August 2022; we have started closely tracking the glibc 2.36 development code in Fedora Rawhide and are addressing any issues as they arise. Given the present schedule Fedora 37 will branch after the release of glibc 2.36. However, the mass rebuild schedule means Fedora 37 will mass rebuild (if required) before the final release of glibc 2.36, but after the ABI is frozen.

The GNU Binutils version 2.38 was released in February 2022; and we have already been using this version of binutils in Fedora Rawhide successfully to build the distribution. Given the present schedule for Fedora 37 we will continue to use Binutils 2.38 for Fedora 37.


Benefit to Fedora

Stays up to date with latest features, improvements, security and bug fixes from gcc, glibc, binutils, and gdb upstream.

The goal is to track and transition to the latest components of the GNU Toolchain.

Scope

  • Proposal owners: Fedora Toolchain Team (gcc, glibc, binutils, gdb, ...) developers need to ensure that gcc, glibc, binutils, and gdb in rawhide are stable and ready for the Fedora 37 branch.
  • Other developers: Given that glibc is backwards compatible and we have been testing the new glibc in rawhide it should make very little impact when updated, except for the occasional deprecation warnings and removal of legacy interfaces from public header files.
  • Release engineering: A mass rebuild is strongly encouraged; #10865
  • Policies and guidelines: N/A (not needed for this Change)
  • Trademark approval: N/A (not needed for this Change)
  • Alignment with Objectives: N/A


Upgrade/compatibility impact

The compiler, the static linker and the the library are backwards compatible with the previous version of Fedora.


Any source level changes required for glibc 2.36 will be noted here: https://sourceware.org/glibc/wiki/Release/2.36#Packaging_Changes

How To Test

The GNU Compiler Collection has its own testsuite which is run during the package build and examined by the gcc developers before being uploaded.

The GNU C Library has its own testsuite which is run during the package build and examined by the glibc developers before being uploaded. This test suite has over 6200 tests that run to verify the correct operation of the library. In the future we may also run the microbenchmark to look for performance regressions.

The GNU Binutils has its own testsuite which is run during the package build and examined by binutils developers before being uploaded. The regression testsuite is run to verify the correct operation of the static linker and attendant utilities.

The GNU Debugger has its own testsuite which is run during the package build and examined by gdb developers before being uploaded. The regression testsuite is run to verify the correct operation of the debugger.


User Experience

Dependencies

All packages do not need to be rebuilt due to backwards compatibility. However, it is advantageous if a mass rebuild is performed during the Fedora 37 cycle. The mass rebuild would ensure all packages can be built with the newer compiler and core runtime.

Contingency Plan

  • Contingency mechanism glibc: If glibc 2.36 proves too disruptive to compiling the distribution we could revert to 2.35, but given that Rawhide has started tracking glibc 2.36, no show-stopper problems are expected. At this point we can still revert to upstream version 2.35 if insurmountable problems appear, but to do so may require a mass rebuild to remove new symbols from the ABI/API.
  • Contingency mechanism binutils: If binutils 2.38 proves too distruptive to assembling and linking the distribution we could revert to 2.37, but given that Rawhide is using 2.38, no show-stopper problems are expected. At this point we can still revert if insurmountable problems appear, but to do so may require a mass rebuild if the defects involve generated binaries.


  • Contingency deadline: Fedora mass rebuild on 2022-07-20.
  • Blocks release?
    • Yes, upgrading to glibc 2.36 does block the release.

Documentation

The gcc manual contains the documentation for the release and doesn't need any more additional work.

The binutils manual contains the documentation for the release and doesn't need any more additional work.

The glibc manual contains the documentation for the release and doesn't need any more additional work.

The gdb manual contains the documentation for the release and doesn't need any more additional work.

Release Notes

The GNU C Library version 2.36 will be released at the beginning of August 2022. The current NEWS notes can be seen here as they are added: https://sourceware.org/git/?p=glibc.git;a=blob;f=NEWS;hb=HEAD

The GNU Binary Utilities version 2.38 was released February 2022. The current release notes can be seen here: https://sourceware.org/pipermail/binutils/2022-February/119721.html

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