Re: [Qemu-devel] [PATCH 04/30] add a header file for atomic operations

[Anthony Liguori]

Paolo Bonzini <address@hidden> writes:

> Il 01/07/2013 15:00, Anthony Liguori ha scritto:
>>> I
>>> > cannot find the commit exactly, but I think mst added specific code for
>>> > that.
>> Right, I'm not questioning whether these functions have strong enough
>> semantics in their implementation, but asking what their contract should
>> be.
>> 
>> Either we should document that these functions have atomic semantics or
>> we should introduce another variant that guarantee atomic access.
>> 
>> I think the later makes more sense since the majority of users probably
>> don't need atomic semantics.
>
> I think many of these loads and stores do, actually; perhaps most.  It
> also matches what hardware does.

Hrm, I'm not sure if that's true.  PCI has an explicit LOCK# bit to
enable exclusive access so my assumption would be that it doesn't by
default.

But either way, we should document the semantics.

Regards,

Anthony Liguori

>
> Paolo