Re: [Xen-devel] Re: [PATCH 2] HVM vcpu add/remove: setup dsdt and madt infrastructure for vcpu add/remove

[Christoph Egger <Christoph.Egger@xxxxxxx>]

On Wednesday 09 December 2009 13:21:17 Keir Fraser wrote:
> On 09/12/2009 12:04, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:
> >> What's the MADT checksum stuff in the DSDT all about? Does the MADT
> >> really have to stay consistent and checksummed after boot - I would have
> >> assumed that it provides a boot-time snapshot of the system only, and
> >> would not be looked at by the OSPM after boot. I haven't looked at the
> >> ASL code in detail but I'll surely bet that the approach is fragile.
> >
> > Ah, this has to do with the _MAT methods doesn't it. Well, I wonder
> > whether the strategy of sharing the _MAT return values and the MADT
> > entries is actually sensible. There seems to be no really good reason to
> > do it -- they should be consistent at boot-time of course, but after boot
> > the MADT isn't expected to remain live and up-to-date I believe? Then
> > each Processor object can define its own MAT buffer which it manages
> > entirely by and for itself.
>
> Hmm, well, the ACPI spec's example does have the entries shared I think.
> Perhaps it does make sense then, although I'm still unsure whether
> maintaining the MADT checksum is required?

Tools like acpidump or iasl may verify the checksum.

Christoph


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