I think we should examine the feature flag in config.guess for LAHF-SAHF. Here is an incomplete list of 64 bit Pentium 4's without the feature:
Pentium 4 506 E0 Pentium 4 516 E0 Pentium 4 511 E0 Pentium 4 519K E0 Pentium 4 HT 521 Pentium 4 HT 531 Pentium 4 HT 541 Pentium 4 HT 551 Pentium 4 HT 561 Pentium 4 HT 571 Pentium 4 HT 3.2F Pentium 4 HT 3.4F Pentium 4 HT 3.6F Pentium 4 HT 3.8F Pentium 4 HT 517 Pentium 4 HT 524 All Family 15, Model 4, steppings N0, R0 Pentium 4 EE 3.73 Too messy to test for them all specially. Can we add a directory called LAHF to core2 and have all nocona processors use only core2 in the build whereas specifically core2 processors can use core2 and core2/lahf. It will be the simplest fix for now until we can implement something more sophisticated. Bill. 2009/3/14 Jason Moxham <ja...@njkfrudils.plus.com>: > > > > > Early Intel CPUs with Intel 64 lacked LAHF and SAHF instructions available in > AMD64 until introduction of Pentium 4 G1 step in December 2005. LAHF and SAHF > are load and store instructions, respectively, for certain status flags. > These instructions are used for virtualization and floating-point condition > handling. > > > I'll find out model numbers soon > > > > On Saturday 14 March 2009 17:20:25 Gonzalo Tornaria wrote: >> On Sat, Mar 14, 2009 at 1:45 PM, Jason Moxham <ja...@njkfrudils.plus.com> > wrote: >> > I pretty sure all core2 cpus have lahf,sahf , it's just some Pentium D >> > dont have it . You can test the lahf_lm feature bit in cpuid to see if >> > it's got it >> >> Tested in: >> >> My laptop: model 6 / family 15 (core 2 duo T5300). >> My desktop is family 15 / model 6 (pentium D 930). >> >> The "lahf_lm" feature is present in both according to /proc/cpuinfo. >> >> Note that the laptop is "low end" core 2 (in the sense it has no VT >> extensions). The pentium D is "high end" (in the sense it has VT >> extensions --- low end would be pentium D 8xx). Maybe that makes a >> difference? >> >> OTOH, the kvm 64 bit virtual cpu (kvm 72) doesn't seem to know about >> the "lahf_lm" (meaning, it won't report it in cpuid, even if the host >> processor has it. I assume the instructions would work anyway.) >> >> Gonzalo >> >> > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "mpir-devel" group. To post to this group, send email to mpir-devel@googlegroups.com To unsubscribe from this group, send email to mpir-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/mpir-devel?hl=en -~----------~----~----~----~------~----~------~--~---
