Re: 32-bit dma allocations on 64-bit platforms

[David Mosberger]

>>>>> On Thu, 24 Jun 2004 20:51:56 +0200, Andi Kleen <ak@xxxxxx> said:

  Andi> A better IO_TLB_SHIFT would be 16 or 17.

Careful.  I see code like this:

		stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT));

You probably don't want IO_TLB_SHIFT > PAGE_SHIFT...  Increasing
io_tlb_nslabs should be no problem though (subject to memory
availability).  It can already by set via the "swiotlb" option.

I doubt swiotlb is the right thing here, though, given the bw-demands
of graphics.  Too bad Nvidia cards don't support > 32 bit
addressability and Intel chipsets don't support I/O MMUs...

	--david
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