Re: [PATCH 11/15] x86: move enabling of io_apic to prepare_cpus

From: Yinghai Lu
Date: Mon Jun 09 2008 - 16:53:36 EST


On Mon, Jun 9, 2008 at 1:12 PM, Maciej W. Rozycki <macro@xxxxxxxxxxxxxx> wrote:
> On Mon, 9 Jun 2008, Glauber Costa wrote:
>
>> This one does enable_IO_APIC in the init_uniprocessor too, and should
>> account for the !smp case.
>
> Hmm, it looks a little bit better, but why do you want to call
> enable_IO_APIC() separately in the first place? There is a comment
> stating: "Enable IO APIC before setting up error vector," but why is it
> needed on 64-bit systems? Especially as the very same system may run a
> 32-bit kernel and then it suddenly would not have to do this anymore?
> Strange...

that enable_IO_APIC() only call record old ioapic/pin for timer and
clear_IO_APIC.

we need clear_IO_APIC before enable setup error vector, in case there
is wrong setting in ioapic by BIOS...

YH
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