[SeaBIOS] [PATCH] vcpu hotplug: Setup vcpu add/remove infrastructure

Gleb Natapov gleb at redhat.com
Fri Jan 29 21:19:16 CET 2010

On Sat, Jan 30, 2010 at 04:14:29AM +0800, Liu, Jinsong wrote:
> Gleb Natapov wrote:
> >> 
> > OK. Let me try to explain it one more time. Currently MADT table
> > resides in memory of type "ACPI DATA" and AML code reads and writes
> > this memory during CPU hot-plug. According to ACPI spec "ACPI DATA"
> > ares can be reused by an OS, so consider what will happen if OS puts
> > its data into memory area where MADT was and later gets cpu hotplug
> > event. Do you see the problem now?
> > 
> I just hesitate ' if OS puts its data ...'.
What is not clear here? OS is free to reuse this memory for whatever it

> Per my understanding, os will not write madt after booting, only AML write madt when necessary (i.e. cpu hotplug).
Your understanding is wrong. Read spec.

> So is it necessary to mark madt as ACPI NVS?
ACPI VNS or reserved. The difference is that OS should save/restore ACPI NVS
memory during S4 transition. Read the spec it is all there.


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