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Re: [Xen-devel] Problem with ACPI recognzing CPUs

To: <eak@xxxxxxxxxx>, <Xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Problem with ACPI recognzing CPUs
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 08 Aug 2007 08:09:27 +0100
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On 7/8/07 18:54, "beth kon" <eak@xxxxxxxxxx> wrote:

> The contents of this table increase linearly, in this case from 0 to 31.
> So, when apic_ids are above 31, as found in the MADT, they can not be found in
> the x86_cpu_to_apicid table by convert_acpiid_to_cpu, leading to the processor
> being "NOT_FOUND" by ACPI.
> Can anyone explain why xen/core/smpboot.c linearly correlates cpu to apic_id,
> causing problems for machines that have large apic_ids? I'm not sure what the
> right solution to this problem is.

I'm not sure there's a better solution than not building/initialising
arch/acpi/processor_core.c on Xen. The processor-specific ACPI code isn't
going to run well on Xen where dom0 VCPUs may migrate around and not even
see all physical CPUs. The warnings you see are scary looking but harmless.

I suspect we've never noticed these before because we build the acpi
processor code as a module that we never load.

 -- Keir

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