Date: Sun, 25 Oct 1998 12:38:14 +1030
From: Greg Lehey <grog@lemis.com>
To: Harlan Stenn <Harlan.Stenn@pfcs.com>, questions@FreeBSD.ORG
Subject: Re: debugger("bt742a")?
Message-ID: <19981025123814.C16609@freebie.lemis.com>
In-Reply-To: <4313.909249492@brown.pfcs.com>; from Harlan Stenn on Sat, Oct 24, 1998 at 01:18:12PM -0400
References: <4313.909249492@brown.pfcs.com>
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On Saturday, 24 October 1998 at 13:18:12 -0400, Harlan Stenn wrote:
> I've been having a problem reading data off a tape drive. I run X, and the
> tape would read for a while and eventually the machine would simply hang and
> I could not change virtual consoles or do anything to find the problem.
>
> I tried reading the tape on another machine. Once it worked, two other
> times I had the same problem.
>
> So I tried it again, but this time I did the restore from the vt0 instead
> of in X. I noticed the kernel was dropping in to the debugger, with a
> "tag" of bt742a.
>
> What's the real problem here, and what can be done to fix it?
UTSL:
$ find /usr/src/sys/ -name "*.c" | xargs grep bt742a
/usr/src/sys/i386/scsi/bt.c: * Note: bt742a/747[s|d]/757/946/445s will return 'E'
/usr/src/sys/i386/scsi/bt.c: u_char id[4]; /* i.e bt742a -> '7','4','2','A' */
/usr/src/sys/i386/scsi/bt.c: Debugger("bt742a");
Looking in that file, we find:
/*
* If the ccb's mbx is not free, then the board has gone Far East?
*/
if (bt_ccb_phys_kv(bt, ccb->mbx->ccb_addr) == ccb &&
ccb->mbx->cmd != BT_MBO_FREE) {
printf("bt%d: not taking commands!\n", unit);
Debugger("bt742a");
}
In other words, you should have got an error message "bt0: not taking
commands". Did you?
I seem to remember having troubles reading tapes with a Buslogic
controller years ago. In this case (BSDI machine), the SCSI subsystem
just hung, reminding me every 30 seconds that it was hanging. It
could be a Buslogic problem. Do you have machines with other
controllers which you could try? You might also see if it works with
the CAM drivers under 3.0.
Greg
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