tape inspired crashes

[stanonik at nprdc.arpa]

Hello,

We've had several crashes recently while trying commit unnatural
acts with a tape drive.  The unnatural acts consist of trying to
recover data past the logical end of tape (two eofs) and trying to
recover data from tapes lacking any eof.  We get a hard error on
the drive, and then panic with either a segmentation or protection
fault.  We expected the hard error (because the drive suddenly finds
itself in the midst of a tape record without seeing some appropriate
preamble), but we didn't expect the panic.  We thought the drive
would find the next interrecord gap, and reading would resume.

At any rate, our configuration is a vax 780 running 4.3bsd.  The
drive is a kennedy 9400 connected to an emulex tc7000, which is
plugged into an emulex v-master on the sbi.  The fault seems to
occur in htustart when retrying the operation, as though htustart
was passed a (partially?) bogus mba_device.

Panic'ing due to a tape error seems a bug.  Anyone dealt with
this?

Thanks,

Ron Stanonik
stanonik at nprdc.arpa