On Thu, Sep 01, 2011 at 09:56:25AM +0200, Paolo Bonzini wrote:
> On 09/01/2011 09:37 AM, Sasha Levin wrote:
> >>> -#define wmb() __asm__ __volatile__("": : :"memory")
> >>> + /* TODO: we may also need rmb()s. It hasn't bitten us yet, but.. */
> >>> + #define wmb() __sync_synchronize()
> >
> >That asm directive also implicitly provided a compiler barrier, I could
> ^^^^
>
> only
>
> >find whether __sync_synchronize() provides one as well.
> >
> >Any idea if it does?
>
> Of course, __sync_synchronize() is a stronger barrier. The asm is
> simply not a synchronization primitive.
Good to hear that confirmed, I hadn't checked myself. But then a cpu
memory barrier primitive without a compiler barrier would be an insane
thing to have.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
