Messages in this thread | | | Date | Thu, 29 Oct 1998 14:05:02 +0100 (CET) | From | MOLNAR Ingo <> | Subject | Re: 4MB pages and framebuffer access, x11perf results, 2.1.125 |
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On Wed, 28 Oct 1998, Linus Torvalds wrote:
> On Thu, 29 Oct 1998, MOLNAR Ingo wrote: > > > > the 4m issue is i think conceptually a granularity thing. Theres nothing > > wrong with unmapping the middle 4M of a 12M framebuffer mapping, no matter > > how rare it would be. > > There _is_ something wrong with it - namely that the VM layer has to know > how. [...]
theres one more reason why it's a granularity type of thing: the vma's virtual address has to be 4M aligned too. Basically mmap() picks a generic 4M-size vma, and only the driver-specific function knows that this is 'incorrect'. We could hack this around by dropping the vma and reallocating it, but this is not quite robust.
-- mingo
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