Re: [Qemu-devel] scsi: lsi problems since "unit attention on reset"

[Paolo Bonzini]

On 09/26/2011 09:27 AM, Jan Kiszka wrote:
> Hi Paolo,
>
> I'm facing problems over latest qemu with our special guest OS that is
> using the LSI controller. It hangs during boot now. This can be resolved
> by reverting commit c7b488721d (scsi: report unit attention on reset).
>
> I cannot exclude a bug in the guest driver at this point, but maybe you
> also have some idea what could go wrong in the SCSI stack or the LSI
> emulation. Any suggestions where to look at would be welcome.

It works for me under Linux, so I suspect it is a bug in the guest OS or 
the BIOS, which should send TEST UNIT READY before trying to communicate 
to the HBA.  You can use tracing to detect that, it probably sends 
something like READ CAPACITY and fails because it does not expect that 
command to fail.

That said, since there are 3 out of 3 BIOSes that couldn't cope with 
that change---Linux and Windows work of course---it makes sense to 
revert it even though the patch by itself is correct.  If you send it 
out, I'll gladly add my Acked-by.

Paolo