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The GNU C Library version 2.24


Switch glibc in Fedora 25 to glibc version 2.24.


Current status

Detailed Description

The GNU C Library version 2.24 will be released at the beginning of August 2016; we have started closely tracking the glibc 2.24 development code in Fedora Rawhide and are addressing any issues as they arise. Given the present schedule Fedora 24 will branch after the GLIBC 2.24 upstream release.

In addition, we plan the following packaging changes:

  • Split NSS (Name Service Switch) modules into separate RPM subpackages (#1338889)
  • Leave assertions enabled (#1338887)
  • Use one program to implement sln and ldconfig (#1315476)
  • Provide a libcrypt implementation not based on (#1324623)

Benefit to Fedora

Stays up to date with latests security and bug fixes from glibc.

The packaging changes will provide a small reduction in disk space needed by minimal installations.


  • Proposal owners: Update glibc to 2.24 from tested upstream release.
  • Other developers: Aside from Carlos O'Donell <>, Florian Weimer <>, Torvald Riegel <>, Martin Sebor <>, and Patsy Franklin <>, no other developers are required. These developers need to ensure that rawhide is stable and ready for the Fedora 24 branch. Given that glibc is backwards compatible and we have been testing the new glibc in rawhide it should make very little impact when updated.
  • Release engineering: In general coordination with release engineering is not required. A mass rebuild is not required.
  • Policies and guidelines: The policies and guidelines do not need to be updated.

Upgrade/compatibility impact

The library is backwards compatible with the version of glibc that was shipped in Fedora 24.

No packaging changes required, see:

How To Test

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 1000+ tests that run to verify the correct operation of the library. In the future we'll also be running the microbenchmark to look for performance regressions as well as behavioural ones.

User Experience

Users will see improved performance, many bugfixes and improvements to POSIX compliance, additional locales, etc. The glibc 2.24 NEWS update will include more details.


All packages do not need to be rebuilt.

Contingency Plan

  • Contingency mechanism: Given that Rawhide has started tracking GLIBC 2.24, no show-stopper problems are expected. At this point, we can still revert to upstream version 2.23 if insurmountable problems appear.
  • Contingency deadline: Alpha freeze.
  • Blocks release? Upgrading glibc does block the release. We should not ship without a newer glibc, there will be gcc and language features that depend on glibc being upraded. Thus without the upgrade some features will be disabled or fall back to less optimal implementations.


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

Release Notes

The GNU C Library version 2.24 will be released at the beginning of August 2016. The current NEWS notes can be seen here as they are added:;a=blob;f=NEWS;hb=HEAD