On Mon, 2002-11-04 at 09:44, Jens Axboe wrote:
> It's probably not a good idea to rely on ata drives that also speak
> atapi, to my knowledge only a few old WDC drives ever did that. Since we
> are basically moving to the point where "SCSI" commands is the
> commandset that the block layer uses to make drivers do things for it,
> I had the idea of doing a rq -> taskfile conversion for ide. Just for
> simple things like read/write and sync cache, basically stuff that is
> directly translatable. That would make Linus' example actually work, and
> it would also make the direct read/write programs using SG_IO work on
> IDE drives as well.
Going beyond IDE it might be cleaner to be able to do
struct bio_command_ops
{
eject: idedisk_eject,
suspend: idedisk_suspend,
identify: idedisk_identify,
...
[maybe even read:/write: in some cases
like smart scsi raids]
}
that way IDE disk and all the other weirdass drives can have -one-
command parser not the twenty differently buggy ones we have now simply
by doing
if(rq_is_command(rq))
bio_do_command(rq, &bio_command_ops);
Its also very convenient as we can add fields to the structure and then
to drives without breaking the API and without so much updating
Alan
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This archive was generated by hypermail 2b29 : Thu Nov 07 2002 - 22:00:32 EST