Re: [PATCH 1/5] Add a global synchronization point for pvclock

[Jeremy Fitzhardinge]

On 04/23/2010 02:31 PM, Zachary Amsden wrote:
> Does lfence / mfence actually serialize?  I thought there was some
> great confusion about that not being the case on all AMD processors,
> and possibly not at all on Intel.
>
> A trap, however is a great way to serialize.
>
> I think, there is no serializing instruction which can be used from
> userspace which does not trap, at least, I don't know one off the top
> of my head.

rsm is not technically privileged... but not quite usable from usermode ;)

    J
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