Re: [Qemu-devel] [PATCH] lsi53c895a: add support for ABORT messages

[Peter Lieven]

On 26.04.2011 19:04, Michael Tokarev wrote:
> 26.04.2011 18:46, Peter Lieven wrote:
> []
> > i recently saw some qemu-kvm 0.12.5 guests with scsi and this patch
> > applies crashing when
> > we updated our backend iscsi storages. (short interrupt in traffic flow,
> > iscsi disconnect + reconnect)
> >
> > i always see:
> > lsi_scsi: error: ORDERED queue not implemented
> >
> > and then either the maschine just hangs or it even aborts due to this
> > assertion:
> > qemu-kvm-0.12.5: /usr/src/qemu-kvm-0.12.5/hw/lsi53c895a.c:596:
> > lsi_reselect: Assertion `s->current == ((void *)0)' failed.
> http://bugs.debian.org/613413 talks about this very issue too ;)
>
> > any ideas?
> Unfortunately, no, except that it looks like scsi support is
> not of production quality still.
Do you know a reliable way to reproduce the ORDERED queue not 
implemented error?
I tried with 0.14.0, but I were not able to. I will now try with 0.12.5.

However in 0.14.0 I manage to freeze a VM when copying data from an SCSI 
device and
then temporarely interrupt the connection to my iSCSI storage which is 
used as backend
on the host. Strangely, I cannot reprocude this when I run qemu-kvm in 
gdb. There I just
see some SIGPIPE errors, but when I continue everything is fine.

From what I read from the SCSI2 specs a target should either implement 
all tagged queue
commands or none. If tagged queing is not supported it should send a 
reject message, but
continue with the following command.

http://ldkelley.com/SCSI2/SCSI2/SCSI2-06.html#6.6.17

Can somebody who is more familiar with SCSI look into this? SCSI drive 
support
seems to be serverly broken.

Peter

> /mjt