Re: Cleanups for APIC

[Maciej W. Rozycki]

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@xxxxxxxxxxxxx, PGP key available        +
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