EXA for radeon experimental patch

Lars Knoll lars at trolltech.com
Thu Sep 1 14:54:53 PDT 2005

On Thursday 01 September 2005 23:16, Michel Dänzer wrote:
> On Thu, 2005-09-01 at 11:35 +0200, Lars Knoll wrote:
> > Even if the card doesn't have scatter/gather support, drm allows you to
> > allocate a piece of consistent physical ram, and mmap it in the server.
> > The handle you get is the physical address, so you should be able to use
> > that to implement PCI dma transfers.
> Are you sure about that, in particular on a 64 bit system? The handle
> may coincide with the physical address in a lot of cases, but I didn't
> think that was guaranteed.

It's probably not guaranteed, but according to what I could see in the drm 
code that's what it is (also on 64 bit systems, the handle is a ulong). Lots 
of the drm code is still a mystery to me. To program the HW I need physical 
addresses, but I don't really see how to get them. The only exception is 
memory that is bound into the GART.


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