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[Xen-devel] Re: [PATCH 03 of 36] x86: add memory barriers to wrmsr



Arjan van de Ven wrote:
On Wed, 25 Jun 2008 14:08:57 -0700
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

Arjan van de Ven wrote:
it's more readable for several of these cases to stick a barrier();
in front and after it to be honest; that makes it more explicit that
these are deliberate compiler barriers rather than "actual" memory
access...

I suppose, though I would be inclined to put the barriers in the
wrmsr macro itself to act as documentation.


yeah I meant like this:

static inline void native_write_msr(unsigned int msr,
                                    unsigned low, unsigned high)
{
        barrier();
        asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high));
        barrier();
}

or in the same in the thing that calls this.


OK, we're in vehement agreement then.

   J


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