Re: [PATCH] cpu hotplug issue

Vasilis Liaskovitis
2011-08-03T16:23:15Z

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.

- Vasilis