Re: MTRR setting and framebuffer driver

Richard Gooch (rgooch@ras.ucalgary.ca)
Tue, 14 Sep 1999 17:08:03 -0600


Jamie Lokier writes:
> Richard Gooch wrote:
> > I agree. I don't like the idea of adding kludges to the MTRR code. It
> > should provide a minimal interface, making no assumptions about PCI
> > regions or anything like that.
>
> > [...] since we are assuming PCI region rules.
>
> I don't think it has anything to do with PCI.
>
> If we can assume that unregistered physical address space is never
> accessed (whatever the bus), it's safe to have MTRRs covering that
> space redundantly.

Erm, OK, so you want something that takes the region as given by
vesafb, checks the MTRR alignment rules, and if necessary scans the
resource tree checking if the "remainder" is unallocated.

I suppose you could do that. But than you'd have to make sure the MTRR
region is removed if something allocates the remainder. Or perhaps
allocate the remainder yourself (and free it when the MTRR is
deleted). This is getting messy.

Definately not something I'd want in the MTRR driver. But a support
function would be OK.

Still, it might be easier to change vesafb instead.

Regards,

Richard....
Old: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca

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