Messages in this thread | | | Date | Mon, 16 Dec 2002 18:36:20 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: Intel P6 vs P7 system call performance |
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On Tue, 17 Dec 2002, Dave Jones wrote: > > I'm sure I recall seeing errata on at least 1 CPU re sysenter. > If we do decide to go this route, we'll need to blacklist ones > with any really icky problems.
The errata is something like "all P6's report SEP, but it doesn't actually _work_ on anything before the third stepping".
However, that should _not_ be handled by magic sysenter-specific code. That's what the per-vendor cpu feature fixups are there for, so that these kinds of bugs get fixed in _one_ place (initialization) and not in all the users of the feature flags.
In fact, we already have that code in the proper place, namely arch/i386/kernel/cpu/intel.c:
/* SEP CPUID bug: Pentium Pro reports SEP but doesn't have it */ if ( c->x86 == 6 && c->x86_model < 3 && c->x86_mask < 3 ) clear_bit(X86_FEATURE_SEP, c->x86_capability);
so the stuff I sent out should work on everything.
(Modulo the missing syscall page I already mentioned and potential bugs in the code itself, of course ;)
Linus
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