Re: [PATCH] cpu hotplug issue

Gleb Natapov
2011-08-04T08:01:56Z

On Wed, Aug 03, 2011 at 06:25:07PM +0200, Vasilis Liaskovitis wrote:
> On Wed, Aug 03, 2011 at 12:42:11PM +0200, Jan Kiszka wrote:
> > >> Why can't Seabios read to true number online CPUs from the PIIX4 device?
> > >> The information is there already, no need for addition PV here.
> > >>
> > > Where is it in PIIX4 device?
> >
> > PROC registers (or however they are called).
>
> In qemu-kvm, the cpus_sts bitmap array in PIIX4PMState/ACPIGPE has the true
> number of online CPUS. This is accessed from the DSDT hotplug method in Seabios
> as "OperationRegion SystemIO" with address 0xaf00. Is this i/o address in the
> piix4 spec? How can it be accessed from the rest of SeaBIOS? It seems to reside
> in ACPI_PM space.
>
0xaf00 is not part of PIIX4. PIIX4 supports nor cpu host plug
neither pci hot plug. I haven't found any PROC register in PIIX4 spec
so far.

--
Gleb.