Re: [2.6.12] x86-64 IO-APIC + timer doesn't work

From: Andi Kleen
Date: Sat Jun 18 2005 - 14:12:50 EST

On Sat, Jun 18, 2005 at 02:52:52PM +0100, Alistair John Strachan wrote:
> Hi,
> I upgraded my nForce3 x86-64 desktop from 2.6.12-rc5 to 2.6.12 today and
> something strange started happening. Waay back in 2.6.x I had problems with
> the "noapic" default for nForce boards on x86-64, and so used the "apic"
> kernel boot parameter to force the apic on; this worked successfully for a
> long time with no timer problems.

apic hasn't been needed for several kernel releases now, since the
timer override problem on the Nforce has been workarounded.

> However, as of 2.6.12 (maybe -rc6, too?) my desktop occasionally fails to boot
> with the message:
> "IO-APIC + timer doesn't work! Try using the 'noapic' kernel parameter."
> (arch/x86_64/kernel/io_apic.c)
> However, this message is intermittent; it is sometimes possible to boot
> without getting it, and everything works fine. So I took its advice and ran
> with noapic, and everything seems fine now.
> However, I just thought I'd let whoever maintains this bit of code know that
> the check isn't a "sure thing": it's not being flagged reliably. Whether this
> is my BIOS or the kernel, I don't know.
> Though I clearly don't require this functionality any more, is there any
> reason I now can't use apic on this nForce3 board, where previously (on
> 2.6.12-rc5 and older) I could?

Are you sure the problem is new?

Can you post the full output of a failing case with apic=verbose?

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