Re: [PATCH v3 1/2] system/memory: Use qemu_ram_{copy, move}() in ram device region accessors

On Fri, 17 Jul 2026 at 14:24, Michael S. Tsirkin <[email protected]> wrote:
>
> On Thu, Jul 09, 2026 at 07:52:12PM +1000, Gavin Shan wrote:
> > Hi Michael and Peter,

> >
> > Could you help to confirm if the conclusion is to have unified qemu_ram_{copy, move}()
> > for all architectures? In qemu_ram_{copy, move}(), the fixed sized accesses like
> > 1/2/4/8 bytes are handled by __builtin_{memcpy, memmove}() and fall back to
> > memcpy/memmove() for other sized accesses. It's basically what was proposed by
> > Michael :-)
>
> No. __builtin_ and  memcpy/memmove are same on modern linuxes.
>
> I'd say as a 1st step, on x86 hosts we can do a fixed size
> memmove for 1/2/4/8, on other hosts
> *aligned* 1/2/4/8 bytes can do
>  __atomic_store ... __ATOMIC_RELAXED
> and the rest can hobble along on memmove
> and hope for the best.

I don't think we should be doing something that's x86-host specific,
as I've mentioned previously.

-- PMM