[parisc-linux] Re: parisc scatterlist doesn't want page/offset

Jens Axboe axboe@suse.de
Fri, 16 Nov 2001 09:33:56 +0100

On Fri, Nov 16 2001, Grant Grundler wrote:
> Hi all,
> Could someone point me to any discussion about adding
> page/offset to struct scatterlist?

See lkml a couple months back, 32-bit dma etc discussion.
> To me, it looks like a half-assed step to support DMA to HIGHMEM
> on 32-bit arches.  TBH, I'd like to see page/offset replace
> address in the pci_map* interfaces and struct scatterlist.
> But then replace it across the board so the DMA mapping code
> doesn't have to decide which field to use (KISS). This really
> belongs in 2.5 kernel.

It's not half-assed, it's needed. I would imagine that pci_map_single
etc stays though, although pci_map_page or pci_map_sg is the preferred

Regarding the patch -- please add a helper function to set the sg list
instead of introducing CONFIG_HIGHMEM all over the place. I'm assuming
you are missing the piece which leaves out page/offset for non-highmem,
if not you are really pedantic about saving a few cycles :-)

Jens Axboe