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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: scsi tape recommendations
Date: 20 Oct 1996 14:21:49 GMT
Organization: Private BSD site, Dresden
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Message-ID: <54dcht$3gs@uriah.heep.sax.de>
References: <29f_9610110039@caamora.caamora.com.au>
<53o3mo$8p4@uriah.heep.sax.de> <333_9610162328@caamora.caamora.com.au>
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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jlm@caamora.caamora.com.au (jlm) wrote:
> ju> I think a simple quirk record would have done it for FreeBSD, too.
>
> sounds good, but what is a quirk (record) ?
A note for a SCSI `type' (i.e. high-level) driver about exceptional
handling required (from what the driver believes to be standard) for
some particular device.
Here's part of my patch again:
static st_modes mode_tandberg4200 =
{
{0, 0, 0}, /* minor 0,1,2,3 */
{0, ST_Q_FORCE_VAR_MODE, 0}, /* minor 4,5,6,7 */
{0, 0, QIC_150}, /* minor 8,9,10,11 */
{0, 0, QIC_120} /* minor 12,13,14,15 */
};
That's a record describing the various tape subdevices. It basically
says that subdevice 0 (/dev/rst0.0 alias /dev/rst0) uses the defaults,
while subdevice 1 (/dev/rst0.1) always forces variable blocklength
mode, and subdevices 2 and 3 hard-wire QIC-150 and QIC-120 density,
respectively. (The latter two should probably also contain
ST_Q_FORCE_FIXED_MODE instead of the second zero.)
{
T_SEQUENTIAL, T_REMOV, "TANDBERG", " TDC 38*", "*",
"st", SC_ONE_LU, ST_Q_SNS_HLP|ST_Q_NO_1024, mode_tandberg4200
},
This means all devices that are of type `sequential access' (aka. tape)
with removable media, and that probe as "TANDBERG TDC 38<something>"
will use the following quirks:
. they will only be probed on a single LUN (they are known to be not
multi-LUN devices),
. they require ``sense help'', i.e. at least one block must pass the
tape head before the MODE SENSE data are useful for the driver,
. they are known to not handle 1024-byte fixed-length records, and
. the record named `mode_tandberg4200' should be used to describe the
subdevices, as opposed to the generic subdevice mode.
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)