Re: HT CPU handling - 2.6.2

[Bill Davidsen <davidsen@tmr.com>]

Hod McWuff wrote:
> I've got a 2.0A GHz P4, advertised as non-hyperthread, that seems to be
> reporting the presence of a second CPU. It also seems to be disabled by
> setting bit 7 of its ID. I've tried compiling with support for 130 CPU's
> and nothing changed. What would have to be done to get this disabled
> CPU half back online?
> 
> Feb  9 04:45:03 pug ACPI: Local APIC address 0xfee00000
> Feb  9 04:45:03 pug ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
> Feb  9 04:45:03 pug Processor #0 15:2 APIC version 20
> Feb  9 04:45:03 pug ACPI: LAPIC (acpi_id[0x02] lapic_id[0x81] disabled)
> Feb  9 04:45:03 pug Processor #129 invalid (max 16)
> Feb  9 04:45:03 pug ACPI: LAPIC_NMI (acpi_id[0x01] dfl dfl lint[0x1])
> Feb  9 04:45:03 pug ACPI: LAPIC_NMI (acpi_id[0x02] dfl dfl lint[0x1])

Look in /proc/cpuinfo for number of siblings. If it's one you have no HT 
capability, the stuff for HT is mostly there but there's no sib to 
share. Sort of like a Siamese twin who's an only child or some such. You 
have a funky APIC and not much else.

Don't know if the LAPIC is actually useful.
-- 
Bill Davidsen, TMR