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

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

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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