2.5: PCI scatter gather list change

2.5: PCI scatter gather list change

[Anton Blanchard]

Hi Jens,

I got 2.5 booting on ppc64 today and noticed that the behaviour of 
sglists has changed. Before we would get an array of sg->address,
sg->length pairs, we now get sg->page, sg->offset, sg->length triplets
(from blk_rq_map_sg).

I dont care too much either way, but if this change is here to stay I'll
let the non intel maintainers know so they can fix up their pci dma
code.

Anton

Re: 2.5: PCI scatter gather list change

[Jens Axboe]

On Sun, Dec 02 2001, Anton Blanchard wrote:
> 
> Hi Jens,
> 
> I got 2.5 booting on ppc64 today and noticed that the behaviour of 
> sglists has changed. Before we would get an array of sg->address,
> sg->length pairs, we now get sg->page, sg->offset, sg->length triplets
> (from blk_rq_map_sg).
> 
> I dont care too much either way, but if this change is here to stay I'll
> let the non intel maintainers know so they can fix up their pci dma
> code.

The change is here to stay, the ->address stuff will die in 2.5.
Consider highmem pages which have no virtual mapping.

-- 
Jens Axboe

Re: 2.5: PCI scatter gather list change

[David S. Miller]

   From: Anton Blanchard <anton@samba.org>
   Date: Sun, 2 Dec 2001 15:35:53 +1100
   
   I dont care too much either way, but if this change is here to stay I'll
   let the non intel maintainers know so they can fix up their pci dma
   code.

Ummm, platforms need to support this format even in 2.4.x
If PAGE is not NULL, "address" applies, else the PAGE+OFFSET
pair applies.  We'll kill "address" very soon in 2.5.x, but it
has to stay around for compatibility in 2.4.x

Look at sparc64 and x86 in 2.4.x, they expect and handle it
correctly already.  IA-64 fixed up their stuff recently too.