CentOS 5 i586 support
CentOS is still used on i586 CPUs and VIA C3 CPUs (which are i686 CPUs, but do not have a cmov instruction). Our goals is to support i586-class CPUs on CentOS 5. This page describes the progress of i586 support.
You can help testing in with the following hardware:
- Real i586 hardware (with enough memory).
- VIA C3-based (pre-Nehemiah) CPUs.
qemu without handling of cmov instructions. This is handy for quick testing, because you can install the i686 version of CentOS 5 with an unpatched qemu, and then test with a patched qemu. Patch: qemu-0.9.0-no-cmov.diff
CentOS 5 currently boots on at least cmov-less i686 CPUs with the following changes (please add confirmation for i586 and VIA C3 CPUs):
- The i586 CentOS Plus (testing) kernel.
- Replacement of glibc.i686 with glibc.i386.
- Replacement of openssl.i686 with openssl.i386.
Some i386 packages don't work, because they introduce cmov instructions through the -ffast-math gcc parameter. Some packages using -ffast-math seem not to call cmov instructions, others using it do. The following packages have -ffast-math in their build logs:
- libao-0.8.6-5 (not affected?)
- libdbi-0.8.1-2.1 (not affected?)
- libdbi-drivers-0.8.1a-1.2.2 (not affected?)
- libogg-1.1.3-3 (not affected?)
- libvorbis-1.1.2-2 (not affected?)
- mikmod-3.1.6-38.1 (not affected?)
- numactl-0.9.8-2 (not affected?)
- vorbis-tools-1.1.1-3 (not affected?)
- mesa-6.5.1-7.2 (confirmed)
- procps-3.2.7-8.1 (confirmed)
Original build logs (affected packages):
Original Build Log: mesa-6.5.1-7.2.build.log.bz2
Original Build Log: procps-3.2.7-8.1.el5.build.log.bz2
We are Currently working on patches to rebuild the affected packages without the -ffast-math for i586 arch only.
We are currently unaware of other issues, and will add them here when they are found.