Re: Kernel panic with 2.4.9-21 accessing tape drive

[Bryce <bryce redhat com>]

Jay Estabrook wrote:

> On Tue, May 14, 2002 at 11:32:51PM -0600, richard@nairnconsulting.ca wrote:
> >
> > I am running RH7.1, kernel 2.4.9-21. I have an alphaserver 1000A 5/333 with
> > a Qlogic ISP1020 onboard scsi, and DEC TLZ09 tape drive.  Whenever I try
> > and tar something up my machine has a kernel panic and freezes up solid.
> > Any ideas?  I have also been unsuccesful on building any other newer
> > kernel...
>
> This is (or should be by now :-) a well-known problem with the stock
> QLogic driver in the 2.4.x kernels.
>
> Easiest solution is to get the tape drive off the SCSI bus that has
> the hard disks, usually by adding another (old) SCSI controller such
> as NCR810 or even another QLogic, to put the tape drive on.
>
> Hardest solution is to use the ported BSD driver offered at
> www.feral.com.  This is known to work very well with otherwise
> "problem" configurations like yours, and work better than the stock
> driver in every instance. Please read and follow the directions
> closely when patching the new driver in.

*nod*
The real (deep) problem is tha the qlogic card can, by itself, reorder it's
tagged queueing on the fly
problem is that the scsi midlayer doesn't see this so what happens is
Kernel            card
1 slot left        reorders and makes 0 slots left
try and insert    OY! I can't take this command! -> overridden command stack ->
oops

This is all down to a design problem in the native qlogic driver. the feral
driver does actually take account of this card feature and won't overwrite it's
stack


Phil
=--=