Re: [PATCH] Intel Alder IOAPIC fix

[ebiederm@xmission.com (Eric W. Biederman)]

James Bottomley <James.Bottomley@steeleye.com> writes:


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

And that is why I believe it tucks the old resource under the new 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 problem of you have an incorrect device tree what do you do yes.
The difference that I see is in how the tree gets wrong, and what
parts of it you want to keep.
 
> 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?

The solution I keep am thinking of is to simply push an IORESOURCE_TENTATIVE
thing out of the way.

What I am thinking is that /proc/iomem would start out looking link:
fec00000-fec08fff : reserved
ffe80000-ffffffff : reserved

And end up looking like:
fec00000-fec00fff : reserved
fec01000-fec013ff : 0000:00:0f.0
fec01400-fec08fff : reserved
ffe80000-ffffffff : reserved

And either put the code to do that in request_resource, or have
a demand_resource thing that does it.  The only thing worth preserving
in the mixed up BIOS case is that find_resource does not allocate that
range for something else.

Eric