Re: [Qemu-ppc] Bug with REPORT LUNS in IBM VSCSI

[Paolo Bonzini]

Il 02/10/2013 17:12, Nathan Whitehorn ha scritto:
> I'm having some trouble with the VSCSI emulation in the pSeries machine.
> It seems that the emulated SCSI target device on the SRP IT_nexus
> properly distributes SCSI commands to its children but does not report
> them in response to a REPORT LUNS request. This happens because it
> forwards REPORT LUNs to target 0 on its child bus instead of answering
> the command itself.

How so?  The SCSI emulation hijacks REPORT_LUNS and does not pass it
down to the device's alloc_req callback, but the request is still
processed as if it came to the device.

Can you give QEMU's command-line?  Can you reproduce the same bug with
an x86 FreeBSD guest using virtio-scsi?

> This prevents at least FreeBSD from seeing any QEMU
> SCSI device that is not internally a LUN on QEMU target 0.
> 
> I can try to draw up a patch, but it would be nice to know if a fix is
> already in progress first. There seemed to be some patches two years ago
> from Paolo Bonzini to add proper support for hierarchical LUNs, but they
> seem to have never been committed.

No, those were too complicated.  Now I've just added channel= and lun=
properties to the scsi-disk device.

Paolo