Re: amd64 panics w/XEN_DOM0, not GENERIC

[Todd Kover <kovert%omniscient.com@localhost>]

This remains an inssue in the 5.0 tree (and presumably in -current).
I've been running under the patched kernel for a few months with no
issue.

-Todd

I said:

 > > > With the GENERIC (+DEBUG+DIAGNOSTIC) kernel, I got:
 > > > 
 > > > stdone error 5 count 32768 resid 0
 > > 
 > > So the device reported an EIO. You didn't get SCSI error messages before
 > > the panic, did you ?
 > > The attached patch may fix the panic, but I'm not sure it's correct.
 > 
 > The panic is now gone and has been the day you wrote the patch.  This
 > has been with both the GENERIC and XEN3_DOM0 kernels.
 > 
 > > It could actually cause the driver to report an error, while the data
 > > actually got written. But I'm not sure what the correct fix would be
 > > in such a case ...
 > 
 > its almost certainly a partial write, though likely at least something
 > got written.  I'm not quite sure what the fix is, though in my case it
 > doesn't much matter as the file being written gets started fresh on
 > a new tape rather than picked up where it left off.  Obviously this
 > doesn't fix the general case...
 > 
 > > I'm also interested to know if the aprint_error_dev("EOM detected") I
 > > added fires up just before "fixing b_resid".
 > 
 > often it does, tho not always.  The EOMs do seem to approximate when an
 > actual tape fils up, thouth at least one of the 'stdone error 5's (Aug
 > 28 01:28 00:00) likely corresponds to a tape not being loaded into the
 > tape drive.
 > 
 > I've attached some relevent sections from /var/log/messages.
 > 
 > thanks again for your help,
 > -Todd
 > 
 > ---<snip>---
 > 
 > Aug 26 13:35:48 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 26 15:34:48 tarvalon /netbsd: st0: EOM detected
 > Aug 26 15:34:48 tarvalon /netbsd: st0: fixing b_resid
 > Aug 26 15:34:48 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 26 15:34:51 tarvalon /netbsd: st0: EOM detected
 > Aug 26 15:36:59 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 26 17:35:47 tarvalon /netbsd: st0: EOM detected
 > Aug 26 17:35:47 tarvalon /netbsd: st0: fixing b_resid
 > Aug 26 17:35:47 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 26 17:35:49 tarvalon /netbsd: st0: EOM detected
 > Aug 26 17:37:58 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 27 00:01:03 tarvalon /netbsd: st0: error5 in st_load (op 1)
 > Aug 27 03:30:06 tarvalon /netbsd: st0: EOM detected
 > Aug 27 03:30:06 tarvalon /netbsd: st0: fixing b_resid
 > Aug 27 03:30:06 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 27 03:30:08 tarvalon /netbsd: st0: EOM detected
 > Aug 27 03:32:17 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 27 05:35:39 tarvalon /netbsd: st0: EOM detected
 > Aug 27 05:35:39 tarvalon /netbsd: st0: fixing b_resid
 > Aug 27 05:35:39 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 27 05:35:41 tarvalon /netbsd: st0: EOM detected
 > Aug 27 05:37:50 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 27 07:37:00 tarvalon /netbsd: st0: EOM detected
 > Aug 27 07:37:00 tarvalon /netbsd: st0: fixing b_resid
 > Aug 27 07:37:00 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 27 07:37:02 tarvalon /netbsd: st0: EOM detected
 > Aug 27 15:22:57 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 27 17:22:05 tarvalon /netbsd: st0: EOM detected
 > Aug 27 17:22:05 tarvalon /netbsd: st0: fixing b_resid
 > Aug 27 17:22:05 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 27 17:22:07 tarvalon /netbsd: st0: EOM detected
 > Aug 27 17:24:15 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 27 19:23:23 tarvalon /netbsd: st0: EOM detected
 > Aug 27 19:23:23 tarvalon /netbsd: st0: fixing b_resid
 > Aug 27 19:23:23 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 27 19:23:26 tarvalon /netbsd: st0: EOM detected
 > Aug 27 19:25:34 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 00:01:03 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 02:55:50 tarvalon /netbsd: st0: EOM detected
 > Aug 28 02:55:50 tarvalon /netbsd: st0: fixing b_resid
 > Aug 28 02:55:50 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 28 02:55:52 tarvalon /netbsd: st0: EOM detected
 > Aug 28 02:58:00 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 05:33:54 tarvalon /netbsd: st0: EOM detected
 > Aug 28 05:33:54 tarvalon /netbsd: st0: fixing b_resid
 > Aug 28 05:33:54 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 28 05:33:56 tarvalon /netbsd: st0: EOM detected
 > Aug 28 05:36:04 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 07:34:59 tarvalon /netbsd: st0: EOM detected
 > Aug 28 07:34:59 tarvalon /netbsd: st0: fixing b_resid
 > Aug 28 07:34:59 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 28 07:35:02 tarvalon /netbsd: st0: EOM detected
 > Aug 28 08:07:02 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 10:41:18 tarvalon /netbsd: st0: EOM detected
 > Aug 28 10:41:18 tarvalon /netbsd: st0: fixing b_resid
 > Aug 28 10:41:18 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 28 10:41:21 tarvalon /netbsd: st0: EOM detected
 > Aug 28 10:43:32 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 > Aug 28 15:46:29 tarvalon /netbsd: st0: EOM detected
 > Aug 28 15:46:29 tarvalon /netbsd: st0: fixing b_resid
 > Aug 28 15:46:29 tarvalon /netbsd: stdone error 5 count 32768 resid 32768
 > Aug 28 15:46:31 tarvalon /netbsd: st0: EOM detected
 > Aug 28 15:48:43 tarvalon /netbsd: st0: error 5 in st_load (op 1)
 >