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

[Gerd Hoffmann <kraxel@redhat.com>]

On 12/07/09 09:28, Hannes Reinecke wrote:
>> 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?

We want limit the bounce buffer size though.  As there seems to be no 
easy way to make sure the guest doesn't submit requests larger than a 
certain limit I guess there is no way around splitting the request into 
pieces for the bounce buffer case.

We could add offset+size arguments to scsi_req_buf() to accomplish this.

cheers,
   Gerd


PS: FYI: I suspect I wouldn't find time this year to continue working on
     this seriously, especially on the time-consuming testing part. Top
     priority right now are finishing touches for the 0.12 release.
     x-mas will be family time.