Re: 3.2.1 Unable to reset IRR messages on boot

From: Konrad Rzeszutek Wilk
Date: Tue Mar 20 2012 - 13:58:47 EST


On Tue, Mar 20, 2012 at 10:59:24AM +0100, Ingo Molnar wrote:
>
> * Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
>
> > 2). Make the Xen layer fake out an IOAPIC - so instead of 0xffffff, make sure to
> > clear the three bits that Suresh' patch is testing for (Ewwwww, I don't actually
> > like that - that stinks of a hack).
>
> In what universe would a hardware virtualization layer emulating
> actual hardware behavior be a 'hack'?

I think I didn't explain myself enough. The 2) "fix" would be basically the minimal work-around
around Suresh's patch so that the test his patch employs passes. That feels to me like a hack -
a band-aid solution. If his code employs more stringent tests in the next release, then I've got
to play catch-up and add more faking off the IOAPIC. That in long term might mean introducing
a pvops for the ioapic_read so that we can selectivity provide the "proper" IOAPIC entries.

The patch I posted thought tries to solve the existing baremetal problem Sureh's patch was for
and also not introduce a regression by only erasing the IOAPIC if there are no dependencies on it.
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