Messages in this thread | | | Date | Wed, 15 Sep 1999 01:16:52 +0200 | From | Jamie Lokier <> | Subject | Re: MTRR setting and framebuffer driver |
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Richard Gooch wrote: > 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.
Aye, I had that in mind -- a hook from the resource allocator. Ugly I know. Perhaps it is less ugly if the MTRR driver maintains a "best effort" list, and it's job is to program the CPU as best it can at any time to satisfy the list. If resource allocations change, that changes the MTRR programming.
> 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.
I don't see how vesafb can do this without doing exactly what you wrote. vesafb cannot assume it has a PCI region. It cannot assume power of 2 alignment.
So vesafb would have to scan the resource tree looking for a parent region. And then how can it be sure the remaining 1.5MB of resource isn't allocated? Hook the tree so the MTRR is removed if the parent region is allocated, or allocate the extra portion (may not be safe).
But the real point is: should vesafb be making assumptions about MTRR alignment requirements? That may change with another CPU, so I think it is the responsibility of the MTRR driver.
-- Jamie
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