Messages in this thread | | | Date | Tue, 21 Nov 2006 18:27:26 +0000 | From | Alan <> | Subject | Re: Problem with DMA on x86_64 with 3 GB RAM |
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On Tue, 21 Nov 2006 17:46:39 +0100 Andi Kleen <ak@suse.de> wrote:
> > > Shouldn't this problem be mentioned somewhere in the documentation, or did I miss something?
The documentation is correct, the implementation is broken. The documented behaviour works for all platforms except one whose maintainer has a problem with it and refuses to follow the spec.
> Possibly, but devices that cannot address at least 4GB are normally > categorized as "hardware bugs" (or less polite descriptions) and those don't > tend to get much airtime in documentation.
The rest of the kernel deals with hardware limitations, 30bit DMA works on the other platforms. This is an x86-64 platform problem. It misimplements the basic pci_ functionality. If it doesn't wish to implement the stuff (and there btw Andi I do think your view has considerable merit) it should fail the set_mask requests.
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