Re: HT CPU handling - 2.6.2

[Athol Mullen]

Len Brown <len.brown@xxxxxxxxx> wrote:
> Your BIOS is reporting the 2nd CPU as disabled, and telling us that it
> has LAPIC id 0x81 = 129.  The ACPI table code prints this out and
> registers the processor anyway, but that chokes because the LAPIC ID is
> way out of bounds.

IIRC, This is what happens with any P4 that sets the HT flag but only
has one logical CPU.  Completely within Intel specs.  I spent several
days struggling with this months ago when I thought that the 2.4GHz P4
I've got was HT capable.  Then I RTFM...

BTW, IIRC, the BIOS of my machine shows "Local APIC Support" instead of
"Hyperthreading Support" if the CPU installed isn't really HT capable.

> I'm thinking that ACPI should not register a processor that the BIOS
> marked as disabled...

The processor counter should find "logical processors present" is one
and ignore the hardware disabled 2nd logical CPU.

> What should you do?  Apparently you've got an HT-enabled platform, BIOS,
> and OS, but do not have an HT-enabled processor.  Your choices are to
> disable HT in the BIOS SETUP to clean up this message, or plug in an
> HT-enabled processor.

Better still, enable Local APIC but not SMP or HT when you build a
kernel.  That way, you get Local APIC support without SMP kernel.

-- 
Athol
<http://cust.idl.com.au/athol>
Linux Registered User # 254000
I'm a Libran Engineer. I don't argue, I discuss.


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