Re: sg regression in 2.6.16-rc5

From: Steve Byan
Date: Fri Mar 03 2006 - 14:11:44 EST



On Mar 3, 2006, at 1:55 PM, Linus Torvalds wrote:



On Fri, 3 Mar 2006, Steve Byan wrote:

On Mar 1, 2006, at 1:42 PM, Linus Torvalds wrote:

I wouldn't expect it to. Most people use ATA for that, and it tends to
have lower limits than most SCSI HBA's (well, at least the old PATA), so
the change - if any - should at most change some of the sg.c limits to be
no less than what SG_IO has had on ATA forever.

Not that I expect people to have a SCSI CD/DVD drive anyway in this day
and age, so the sg.c changes probably won't show up at all.

CD-ROM support is a frequently-requested feature on the iSCSI Enterprise
Target (iet) email list. It won't be long before iSCSI CD and DVD devices
start showing up, although the underlying hardware will be ATAPI or else
missing entirely (i.e. ISO image file).

Yes, but the point that the ATA limits tend to be on the low side still
stands.

For example, I think the IDE driver defaults to a maximum transfer of 256
sectors, and the same number of max scatter-gather entries. Some
controllers will actually lower that, due to silly hw problems.

The point being that it has worked fine for IDE, and if a SCSI controller
has noticeably lower limits than that, there's something really strange
going on, like a real bug.

Yes, you are correct. I wasn't intending to contest your main point. I only intended to point out that ignoring bugs because no-one uses SCSI DVDs will soon lead to much grief.

Regards,
-Steve
--
Steve Byan <smb@xxxxxxxxxxx>
Software Architect
Egenera, Inc.
165 Forest Street
Marlboro, MA 01752
(508) 858-3125


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