Re: [RFC PATCH] HP (Compaq) Smart Array 5xxx controller SCSI driver

On Sat, 2008-07-19 at 19:52 +0900, FUJITA Tomonori wrote:
This is a SCSI driver for HP (Compaq) Smart Array 5xxx controllers.

SCSI people can skip the following two paragraphs.

Currently, a driver for HP (Compaq) Smart Array 5xxx controllers is
implemented as a block device driver, block/cciss.c (aka, cciss). But
the controller interface is SCSI-3 compatible. The specification says,
"A controller that supports CISS is considered to be a SCSI storage
array controller". A scsi driver for the controllers was discussed
several times.

I think that a SCSI cciss driver can be much simpler (and
maintainable) than the block cciss driver (the majority of the code
forging SCSI command can go away, we have the proper sysfs entries for
free, we can handle scsi tape drives easily etc). It would be helpful
for distributions too since they don't need stuff specific to cciss
(such as udev rules).


There isn't any easy migration path for users. So I think that we need
to keep the block and scsi drivers for cciss for some time (say two
years).

Actually, I think we can make one (which is really required ... it's a
lot of pain to move device nodes, just look at libata). It should be
child's play to come up with a udev rule that simply does extra symbolic
links from /dev/cciss<n>c<n>p<n> to whatever the sd device is. That
should hide a lot of the problem.

The other issue is plugging the management ioctl in, but that can be
done via scsi_host->ioctl.

James


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