On Sat, 27 Nov 1999, Aaron Tiensivu wrote:
> I've wondered this a while and it seems like it would make sense for
> Uni-processor boards to use an IO-APIC also. Lots of people have had
> trouble with sharing IRQs/etc and IO-APIC is a lot more elegant than
> the age old XT pic on most boards. Is it just a matter of cost? Does
> Intel's IO-APIC chip carry a cost they don't want to carry?
i guess part of the picture is cost, but also the fact that 1) Windows
doesnt use the IOAPIC at all 2) NT uses it only in SMP mode, just like
Linux. Why build hardware at a higher cost that no OS supports?
> Personally, I think I'd buy a uni-box with an IO-APIC, it would
> certainly help bang out some bugs because SMP boxes are still somewhat
> rare.
as far as the kernel goes: i did the related changes to decouple the
IOAPIC from SMP about a year ago already - some of the SGI VisWS boxes
were UP but used an IOAPIC.
i believe it should work already: enable the CONFIG_IOAPIC line in your
.config - it should compile and boot i believe.
(there is one case where it's useful and it was mentioned here some time
ago: dual board with a single CPU running UP kernel with IOAPIC
interrupts.)
-- mingo
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