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SubjectRe: [patch] enabling APIC and NMI watchdog on UP systems
On Fri, 29 Sep 2000, Ingo Molnar wrote:

> i'm wondering wether this missing clear_APIC() could explain some of the
> more mysterious boot problems we had?

I don't think so. Unless we have an i82489DX APIC in th PIC mode, the
BSP APIC must be set up into the Virtual Wire mode or DOS, etc. won't
work. AP APICs might be setup randomly, though. Clearing of APICs should
not hurt but we have to take care not to lose any interrupt, as this may
lead to a lockup (especially in the "noapic" mode).

In case of mysterios problems, I would study the setup code paths
thoroughly, though. APICs tend to lose interrupts when the respective
entries are disabled and the source might not be willing to reassert the
IRQ (see the problem with the 8259A glue logic with certain EISA boards,
for example).


+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+ e-mail:, PGP key available +

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