Re: [patch 134/149] x86, paravirt: Add a global synchronization point for pvclock

Peter Palfrader
2010-07-13T17:25:28Z

On Tue, 13 Jul 2010, Avi Kivity wrote:

> On 07/13/2010 07:40 PM, Avi Kivity wrote:
>> On 07/13/2010 07:34 PM, Avi Kivity wrote:
>>>
>>> My bet is that dropping 'static' will fix it. We may have the wrong
>>> constraints on atomic64_cmpxchg64(), so the compiler thinks we never
>>> change last_value.
>>>
>>
>> The constraints are there, but maybe the toolchain is confused.
>>
>
> No they aren't, as Linus just pointed out. His patch should fix the
> problem.

Linus's patch touches __xchg() whereas we're using __cmpxchg() in this
particular case I think.

At least, applying it to my 2.6.32.16 tree didn't help, last_value was
still read-only. Or I backported it wrong.
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