[Xen-devel] Re: [PATCH RFC V4 09/10] x86/jump_label: use GENERIC_NOP5_ATOMIC instead of jmp5 +0

["H. Peter Anvin" <hpa@xxxxxxxxx>]

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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