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SubjectRe: Cleanups for APIC
On Thu, 27 May 2004, Ingo Molnar wrote:

> > Hmm, isn't that needed to make sure the iomem writeback is completed
> > before exiting the caller?
>
> the only thing that could happen is a POST delay in the PCI chipset - but
> is that really an issue? Plus we only do the io_apic_sync() for the
> masking, not the unmasking - so if it's needed then we dont do it
> consistently.

The I/O APIC need not be hooked to PCI ;-) -- I'm not sure about the
i82093AA, but that's definitely true for the i82489DX. The call to
io_apic_sync() is needed for masking to make sure interrupts won't be
dispatched after returning from the call -- this is not needed for
unmasking as a delay here is harmless.

Though, now that we don't mask APIC interrupts during their service
anymore the synchronization may be superfluous indeed -- other cases have
to take late interrupts into account anyway.

--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@ds2.pg.gda.pl, PGP key available +
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