> > I wonder why there is a command to turn on DMA on disks. Could
> > it be that some disks don't work with DMA on?
> sure. it's PC hardware, so it's crap :-)
unfortunately, this isn't a pc hardware thing. pata
devices are not required to support dma. ata 7, which
is the first to include sata support, requires udma mode
5 support. (many sata:pata bridges violate this part of
the spec, e.g. sata doms.)
but i'm wondering if dma support isn't a red herring.
> sdC0 is a cdrom. I can turn dma on for my sata disks (sdE0/sdF0) no problem.
it could be that this is a chipset that advertizes sata and
pata pci devices concurrently, but only one may be accessed
by the operating system. some ich 7 chipsets fall into this
category.
does this also hang your machine?
echo probe|scuzz
if so, i would put some debugging in atapktio.
otherwise, it just might be a bug in sdata.c
- erik
