Talk:Features/F12X86Support

We can support i586 processors by handling CMOV invalid instruction in kernel
 * Dmalcolm 18:02, 15 June 2009 (UTC) If a Fedora user wants to verify that a CPU will work with F12, how should he/she query /proc/cpuinfo ? (and does smolt have any of this data?)  Thanks
 * Bill Nottingham Once a set has been decided on, this should be pretty trivial. With respect to the proposal, 'grep sse2 /proc/cpuinfo' should work.
 * Bruno: Is there a way to tell which binaries actually use SSE2 instructions so that a secondary arch targeting athlons would be able to inherit safe binaries from the i686+ arch?
 * Bill Nottingham This part of the change was reverted.


 * Neal Gompa: Pentium II and lower do not support SSE or SSE2. Pentium III only supports SSE, not SSE2. Pentium 4 supports SSE2 and SSE3. However, all Pentium chips (Pentium Pro and higher) support i686 + MMX. If we wanted to move to i686, a secondary arch offering no SSE2 would be a good idea.
 * Aleksandar Kostadinov: I would second that SSE2 is a overkill. Why is not MMX enough? In fact I own an Athlon desktop that is pretty much enough for my work and I would have still worked on that if other factors wouldn't force me to entirely use my laptop (that's not much faster btw).
 * Bill Nottingham This part of the change was reverted.


 * Michael Osborne: This change will break Fedora on Via C3 processors. These are used quite a bit for mini-itx boards for LTSP terminals as they don't require active cooling. A lot of breakage for little gain AFAICS.


 * Bill McGonigle: There's an extensive thread on this on fedora-devel. Many questioned the wisdom of abandoning so much hardware for a meager 1-2% performance gain.


 * W. Michael Petullo: See also https://bugzilla.redhat.com/show_bug.cgi?id=523559.
 * Why is my processor no longer supported in order to support a negligible performance gain (~1%)?
 * Could we not support both new and old processors using two release architectures?
 * Do we not want to support the embedded market?
 * One historic advantage of Open Source was the ability to inject new life into old hardware. Do we want to lose this?
 * Why is OLPC used as a benchmark for worthy processors? If altruism is a motivation for this cut-off, then it seems allowing Fedora users to continue to use old hardware will do more then OLPC will (based on the OLPC statistics on Wikipedia -- enough have been donated to equip 0.0002% of the world population -- compared to VIA's processor sales).

CMOV support
We could maintain support for i586/C6 by handling CMOV invalid instruction interrupt in kernel.