Messages in this thread | | | Date | Thu, 14 Aug 2008 15:26:58 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [RFC PATCH] x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug |
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Jeremy Fitzhardinge wrote: > Mathieu Desnoyers wrote: >> I'm just worried about this comment from Harvey Harrison : >> >> arch/x86/mm/fault.c : is_prefetch() >> >> * Values 0x26,0x2E,0x36,0x3E are valid x86 >> prefixes. >> * In X86_64 long mode, the CPU will signal >> invalid >> * opcode if some of these prefixes are >> present so >> * X86_64 will never get here anyway >> > > I would say that comment is wrong. But we'd never put a lock prefix on > a prefetch, so you won't be added a ds prefix either. >
Locking prefetches is definitely wrong :)
I don't know if the comment is correct; I've certainly never heard of that myself.
-hpa
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