Re: Emulating CPUs with larger atomic accesses

[Richard Henderson]

On 5/13/22 03:00, Florian Weimer wrote:
> What's QEMU's approach to emulating CPU instructions that atomatically
> operate on values larger than what is supported by the host CPU?
>
> I assume that for full system emulation, this is not a problem, but
> qemu-user will not achieve atomic behavior on shared memory mappings.
> How much of a problem is this in practice?

Well, it doesn't work, no.  In practice, x86_64 supports 128-bit atomic operations, and 
guest requires more than that.  No one really cares anymore about 32-bit hosts with 
smaller atomic operations.


r~