Re: [PATCH] Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1)

Jeff Garzik
2004-10-27T21:31:11Z

On Wed, Oct 27, 2004 at 02:29:14PM -0700, Andrew Morton wrote:
> spose so. The scatterlist API is being a bit silly there.

Well, it depends on your perspective :)

Each scatterlist entry is supposed to map to a physical segment to be
passed to h/w. Hardware S/G tables just want to see a addr/len pair,
and don't care about machine page size. scatterlist follows a similar
model.

dma_map_sg() and other helpers create a favorable situation, where >90%
of the drivers don't have to care about the VM-size details.
Unfortunately those drivers that need need to do their own data transfer
(like ATA's PIO, instead of DMA) need direct access to each member of an
s/g list.

Jeff