Re: [Qemu-devel] [sneak preview] major scsi overhaul

[Hannes Reinecke]

Gerd Hoffmann wrote:
> On 11/27/09 12:08, Gerd Hoffmann wrote:
>> On 11/26/09 16:50, Hannes Reinecke wrote:
>>> So indeed, this approach would only work if we signal some sense code
>>> back to the host.
>>> I, OTOH, don't have any qualms with returning HARDWARE_ERROR,
>>> 0x26/0x08(TOO MANY SEGMENT DESCRIPTORS) resp 0x26h/0x0B (INLINE DATA
>>> LENGTH EXCEEDED).
>>> Feels only fair to notify the guest it has done something wrong.
>>
>> Also set the info field which linux uses to figure how many sectors it
>> actually got.
> 
> Hmm.  Well.  Seems to work out at least for linux, i.e. it figures it
> got a bunch of sectors and tries to continue.  Linux logs an I/O error.
>  Also I didn't try other guests (yet).
> 
> Using that as a way to limit scsi-disk request sizes probably isn't a
> good idea.  For scsi-generic that would be a improvement over the
> current situation though.
> 
Yes, quite.

But for scsi-disk we could always fallback to using bounce-buffers,
could we not?
Provide we get a detailed enough error code, but this could be arranged
methinks.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                   zSeries & Storage
address@hidden                        +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)