[coreboot] Resource Allocation discussion

[Myles Watson]

> -----Original Message-----
> From: Marc Jones [mailto:marcj303 at gmail.com]
> Sent: Tuesday, December 02, 2008 7:52 PM
> To: Myles Watson
> Cc: ron minnich; Rudolf Marek; Coreboot
> Subject: Re: [coreboot] Resource Allocation discussion
> 
> On Tue, Dec 2, 2008 at 3:23 PM, Myles Watson <mylesgw at gmail.com> wrote:
> >
> >
> >> -----Original Message-----
> >> From: ron minnich [mailto:rminnich at gmail.com]
> >> Sent: Tuesday, December 02, 2008 2:51 PM
> >> To: Myles Watson
> >> Cc: Marc Jones; Rudolf Marek; Coreboot
> >> Subject: Re: [coreboot] Resource Allocation discussion
> >>
> >> On Tue, Dec 2, 2008 at 11:33 AM, Myles Watson <mylesgw at gmail.com>
> wrote:
> >>
> >> > Do we want to take fixed resources into account in the allocator?
> >>
> >> I would think so.
> >
> > I would too, but v2 didn't and did pretty well.  I'm interested to see
> an
> > idea for the resource allocation algorithm that allocates from largest
> to
> > smallest resource, except when it's skipping fixed resources.
> >
> > I think it's doable, but nothing like what we have.
> 
> That surprises me. I thought it does, which is how/why you can get rid
> of DEVICE_MEM_HIGH. Otherwise you would clobber the ROM and the APIC.

You're right.  I think it's broken.  That's why right now I'm setting the
base to 0xfc000000 manually.  Thanks for pointing it out. 

I'd assumed that resource_max took fixed resources into account, but it
doesn't.  All resource_max does is align the resource based on its limit.

So maybe we need to traverse the tree looking for fixed spaces, and
constrain the domain's resource limit and base.  That wouldn't be too hard.
What I was saying would be hard is interleaving fixed resources with movable
resources.  In other words, if we put the VGA ROM between the two APIC
allocations to save space.  I think that's too ugly.

I'll add a traversal to the tree that doesn't ignore fixed resources.

> And that brings up where to reserve the ROM space. In the southbridge
> subtractive device code I guess?

Sure.  How much do we reserve?  Is it southbridge dependent?

Thanks,
Myles