[SeaBIOS] [PATCH] cpu hotplug issue

Gleb Natapov gleb at redhat.com
Thu Aug 4 10:01:56 CEST 2011


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.



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