Alan Cox wrote:
On Iau, 2005-12-08 at 19:52 +0800, Austin Yuan wrote:
buffer. Because the interface of "alloc_by_type" only receives a
simple parameter "type", here I hide the user space address into
"type" and re-get it in alloc_userspace_memory.
That should probably be fixed by extending the API to pass both
I use this interface to easily implement XAA readpixmap/imagewrite
driver interfaces, and get a better performance. Here, I didn't attach
the patch for i810 driver. I just want to get some comments about it,
and if you think it makes sense, I'd like to make it more generic.
Any comments are appreciated, thanks.
The one thing I don't understand looking at this is that I understood
AGP pages should be marked uncached. However user space pages may exist
in many mappings and the CPU also requires all mappings of a page are
consistent.
Does i8xx need the page uncached or is it enough to wbinvd the pages in
question on writing and invalidate them before reading, or does the i8xx
in fact take full part in the cache coherency ?
I believe the hardware can deal with both cases, and has rules for what uses
each type of memory can be applied to. I think that it's ok to use snooped
memory (in their parlance) for upload type tasks, but not for things like render
destinations. I'll try and be more specific when I get time to review the docs.
I'm pleased to see someone has taken on this much-talked about task. Austin -
have you gotten any feel for how quick this sort of "upload" might be?
Keith
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