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Re: [RFC PATCH, i386]: PR 36793: x86-64 does not get __sync_synchronize right


On Sun, Nov 23, 2008 at 11:57 AM, Ross Ridge <rridge@csclub.uwaterloo.ca> wrote:
> H.J. Lu writes:
>>I am not sure how useful that is for 32bit since it will generate a
>>nop for most machines which do need mfence.
>
> I don't understand what you're saying.  Using "lock orb" should result
> in a memory fence on any IA-32 SMP system, old or new.  It's just a more
> heavyweight way of ordering loads and stores.
>
> The Linux kernel apparently takes the same approach, using either "lock
> addl" or "mfence" depending on whether SSE2 instructions are available
> at compile time.
>

I see.

-- 
H.J.


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