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

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

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.  Either way, I don't think there's 
any legitimate reason to let the compiler reorder things around a wrmsr, 
and it should be an inherent property of the macro, rather than relying 
on ad-hoc barriers where it gets used.  After all, that's a fairly 
accurate reflection of how the micro-architecture treats wrmsr...
   J

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