Re: [PATCH] Intel Alder IOAPIC fix

From: Eric W. Biederman
Date: Thu Jan 15 2004 - 00:26:39 EST


James Bottomley <James.Bottomley@xxxxxxxxxxxx> writes:

> On Mon, 2004-01-12 at 19:25, Linus Torvalds wrote:
> > I think BARs 1-5 don't exist at all. Being set to all ones is common for
> > "unused" (it ends up being a normal result of a lazy probe - you set all
> > bits to 1 to check for the size of the region, and if you decide not to
> > map it and leave it there, you'll get the above behaviour).
> >
> > I suspect only BAR0 is actually real.
>
> OK, I cleaned up the patch to forcibly insert BAR0 and clear BARs 1-5
> (it still requires changes to insert_resource to work, though).

When I looked at the ia64 code that uses insert_resource (and I admit I am
reading between the lines a little) it seems to come along after potentially
allocating some resources behind some kind of bridge and then realize a bridge
is there.

Which is totally something different from this case where we just want
to ignore the BIOS, because we know better. I have seen a number of
boxes that reserver the area where apics or ioapics live. So I think
we need an IORESOURCE_TENTATIVE thing. This is the third flavor of
thing that has shown up, lately.

Want me to code up a patch?

Eric
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