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SubjectRe: [RFC PATCH] x86 alternatives : fix LOCK_PREFIX race with preemptible kernel and CPU hotplug
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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