> From: se@zpr.uni-koeln.de (Stefan Esser)
> Date: Tue, 23 Jan 1996 01:45:13 +0100

> On Jan 19, 11:36, Curt Sampson wrote:
> } Subject: Re: NCR Driver Problems
> } On Fri, 19 Jan 1996, Stefan Esser wrote:
> 
> There is one new explanation for your problems,
> which was found by somebody doing extensive tests
> under FreeBSD. Seems that the generic SCSI code 
> may cause problems with certain drives !
> 
> Please try, whether the following patch can be 
> applied to NetBSD. It removes a call to start 
> the SCSI drive, in case it doesn't power up by
> default. A few drives seem to strongly dislike
> this command, after they once received a command
> with a tag!

Any drive which "does not like" the start command does not
comply with the SCSI-II specification.  I object to this
proposed change because I have SCSI drives that will NOT
spin-up until they receive a start command.

One alternative would be to add a "disk quirk" that says
"do not send start/stop" to this disk and set that for
any disk that "does not like" start commands.

> Please let me know, whether this patch makes any 
> difference!

Yes, it makes my SCSI drives stop working...
(An IBM, a Maxtor, ...)

> Index: /sys/scsi/sd.c
> ===================================================================
> RCS file: /usr/cvs/src/sys/scsi/sd.c,v
> retrieving revision 1.83
> diff -C2 -r1.83 sd.c
> *** sd.c	1996/01/05 20:12:49	1.83
> --- sd.c	1996/01/22 23:32:26
> ***************
> *** 311,315 ****
> --- 311,317 ----
>   	 * not needed for  most hard drives (ignore failure)
>   	 */
> + #ifdef undef
>   	scsi_start_unit(sc_link, SCSI_ERR_OK | SCSI_SILENT);
> + #endif

> Well, the error messages of the FreeBSD version are a lot
> more detailed ... 

> It is well possible, that it fully supports tags. 
> It is just picky about non-tagged commands (even
> NOP commands) sent when any tagged command is 
> active.

I think the SCSI-II spec. allows targets to be picky about that
(my recollection is that it breaks "contingent alliegance"...)

} As per usual on this thread, please cc to both me and Stephen as neither
} of us is on the NetBSD-current list.
Sorry, the mail I saw included only Stefan's address.

Gordon Ross