Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMICinstead of jmp5 +0
From: H. Peter Anvin
Date: Fri Oct 14 2011 - 17:53:00 EST
On 10/13/2011 09:50 AM, Jeremy Fitzhardinge wrote:
> On 10/13/2011 08:40 AM, H. Peter Anvin wrote:
>> On 10/12/2011 05:08 PM, Jeremy Fitzhardinge wrote:
>>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
>>>
>>> GENERIC_NOP5_ATOMIC should make a better nop.
>>>
>> On 32 bits, yes. On 64 bits you should use P6_NOP5_ATOMIC.
>
> So the cleanest way of fixing that is to make the GENERIC_NOP* be
> defined to P6_NOP* on 64-bit then? Assuming I'm correct in guessing
> that the intent of GENERIC_NOP* is "a basically good-enough NOP that
> will work on any x86".
>
No, GENERIC_NOPs are not valid on 64 bits at all.
-hpa
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