Re: [Qemu-devel] [PATCH] Inter-VM shared memory PCI device

Paul Brook
2010-03-10T11:13:21Z

> >> As of March 2009[1] Intel guarantees that memory reads occur in order
> >> (they may only be reordered relative to writes). It appears AMD do not
> >> provide this guarantee, which could be an interesting problem for
> >> heterogeneous migration..
> >
> > Interesting, but what ordering would cause problems that AMD would do
> > but Intel wouldn't? Wouldn't that ordering cause the same problems
> > for POSIX shared memory in general (regardless of Qemu) on AMD?
>
> If some code was written for the Intel guarantees it would break if
> migrated to AMD. Of course, it would also break if run on AMD in the
> first place.

Right. This is independent of shared memory, and is a case where reporting an
Intel CPUID on and AMD host might get you into trouble.

Paul