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SubjectRe: [BUG][2.6.0-test3-bk7] x86-64 UP_IOAPIC panic caused by cpumask_t conversion
Mikael Pettersson <> writes:
> Nasty.
> But why does i386/UP work?

On Wed, Aug 20, 2003 at 01:39:10AM +0200, Andi Kleen wrote:
> > (I believe this is the correct thing to do, except having
> > CONFIG_X86_IO_APIC in generic code isn't quite right.)
> Better would be to undo the cpumask_t changes in io_apic.c
> and go back to unsigned long masks there again.
> Obviously a cpu mask is not the right data structure to manage APICs
> Another way would be to do whatever i386 does to avoid the problem.
> The IO-APIC code is unfortunately quite out of date/unsynced compared to i386,
> maybe it just needs some bug fix ported over. I will check that later.

Odd; I have a UP IO-APIC ia32 box here and it appears to do okay; there
is a question of sparse APIC ID's and APIC ID space needing to be
independent of NR_CPUS handled in the ia32 code that isn't handled in
the x86_64 code. It was handled for ia32 by using a bitmap of size
MAX_APICS (physid_mask_t) instead of cpumask_t for the things, which
appears to eliminate various special cases for xAPIC's too.

-- wli
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