Re: [PATCH 0/3] fix GART to respect device's dma_mask about virtual mappings

[Andi Kleen <andi@firstfloor.org>]

On Tue, Sep 23, 2008 at 04:12:33AM +0900, FUJITA Tomonori wrote:
> Sure, pci-nommu's map_sg/map_single doesn't handle it. But we handle
> this issue somewhere else (like b44 keeps own DMA buffer)?

Yes, b44 handles it on its own. It has to for 32bit which always
has a nop map_sg/single. Also some other subsystems like the block layer
do it implicitely.

> 1. not all map_sg/map_single (e.g. pci-nommu) can't handle it.

and especially i386

> 2. we already have workarounds for it somewhere else so
> map_sg/map_single don't need to handle it.
> 3. I changed GART map_sg/map_signle to handle it. I thought if it
> can handle it, for example, b44 doesn't go the workaround path. It
> would be a good thing.
> 4. But GART cannot remap to addresses < 4GB reliably, so my above
> argument doesn't always work.
> 5. Then my patch doesn't break anything but it's almost meaningless.

Correct.

-Andi
-- 
ak@linux.intel.com