Re: [PATCH] Intel Alder IOAPIC fix

[James Bottomley]

On Thu, 2004-01-15 at 00:18, Eric W. Biederman wrote:
> 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.

Ah, that explains why it's expecting to find the new resource covering
the old one.

> 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?

Well, I'm not sure there's a need for it.  It seems to me that all
insert_resource is supposed to be doing is saying "I've got this
resource here that should have been placed into the tree...please do it
now".

The ia64 I forgot this bridge, and the Alder IO-APIC this PCI BAR is
actually the IO-APIC and thus part of the reserved BIOS area look to be
similar aspects of the same problem.

The only difference (which is what I needed the patch for) was that the
Alder resource needs to go underneath the bios reserved area.

How are you proposing that IORESOURCE_TENTATIVE should work?

James


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