Re: [Xen-devel] x86-64 tools fix question

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Keir Fraser wrote:

> On 1 Mar 2005, at 19:56, Jerone Young wrote:
>
> >     I would like to discuss is this correct, dead wrong, or even 
> > needed at
> > all?
>
> x86/64 has proper barrier instructions -- see 
> include/asm-x86_64/system.h in Linux. It is from there that we should 
> pull our definitions. Barrier macros are defined in a few places in 
> the tools -- we ought to pull them all into one single header 
> incorporated by all tools that need it.
I was just about to send this out myself :-)  I think the consensus was 
to put them all in xc.h.  I posted a patch recently that made everything 
include asm/system.h.  All it should take is replacing asm/system.h with 
xc.h in the patch and then making the necessary changes to xc.h.
For reference, the proper x86-64 barriers are:

#define mb()     asm volatile("mfence":::"memory")
#define rmb()    asm volatile("lfence":::"memory")
#define wmb()    asm volatile("sfence":::"memory")

Regards,
Anthony Liguori

--
Regards,

Anthony Liguori



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