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Re: [Xen-devel] [RFC PATCH V2 2/4] Tool/ACPI: DSDT extension to support more vcpus

On Fri, Sep 01, 2017 at 04:10:26AM -0600, Jan Beulich wrote:
> >>> On 01.09.17 at 11:41, <roger.pau@xxxxxxxxxx> wrote:
> > I'm not sure why lapic_id needs to be a hook in any case, both it's
> > callers use the same exact formula (cpu_id * 2).
> You're aware that this is meant to be improved rather sooner than
> later. At that point I'm then not sure a suitable LAPIC_ID() macro
> could be created, as the potential users of this may not have
> available all necessary inputs. I'd strongly suggest finding a way
> to dynamically insert the APIC IDs (as found while booting) into
> the ACPI tables. That's pretty likely how real BIOSes have to do
> it too.

There's a further problem here, which is that the DSDT is created at
tools compilation time, there's no way to know the APIC IDs at that
point in order to decide whether a CPU gets a Processor or a Device

Leaving the DSDT issue aside, there's also the problem that the MADT
for PVH guests is build by the toolstack, not the firmware (because
there's none), so it's impossible to do it like real BIOSes.

So AFAICT we either remove the hook and code the logic to get the ACPI
ID inside libacpi, or we introduce yet another open coded one in order
to generate the DSDT from mk_dsdt.c


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