Re: [Qemu-devel] [RFC] Memory API

[Anthony Liguori]

On 05/19/2011 03:44 AM, Avi Kivity wrote:
> On 05/19/2011 11:30 AM, Jan Kiszka wrote:
> > >>
> > >> That's not that simple. We need to tell apart:
> > >> - if a cpu issued the request, and which one => forward to APIC
> > > And cpu mode may affect where access is forwarded to. If cpu is in SMM
> > > mode access to frame buffer may be forwarded to a memory (depends on
> > > chipset configuration).
> >
> > So we have a second use case for CPU-local I/O regions?
> >
> > I wonder if only a single CPU can enter SMM or if all have to. Right now
> > only the first CPU can switch to that mode, and that affects the
> > behaviour of the chipset /wrt SMRAM mapping. Is that another hack?
>
> It's a hack. SMM is a per-cpu setting. Effectively it's another address
> pin - it changes the meaning of (potentially) all addresses.

Hrm, this may be splitting hairs, but the chipset enables SMM globally. 
 The processor can enable it by raising a pin but there is only a 
single pin.

It may raise/lower the pin on every load/store, but from the chipset's 
perspective, it's a global setting (at least in the i440fx).

Regards,

Anthony Liguori

>