On Sun, Aug 19, 2012 at 7:58 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > Il 17/08/2012 04:36, Ronnie Sahlberg ha scritto: >> There is no bdrv_* API for the commands for burning a blank MMC disk >> so when iSCSI LUNs are specified and the LUN is a MMC device with >> 0 available blocks. This is a blank disk so force scsi generic. >> >> This allows the guest to talk directly to the target to burn data on >> the disk. >> >> Signed-off-by: Ronnie Sahlberg <ronniesahlb...@gmail.com> > > What happens without the patch? It's ok that scsi-{hd,cd} does not > work, but do scsi-{block,generic} work without the patch? >
Neither of them work, basically because in block.c:find_image_format() if bs->sg is not set in if (bs->sg || !bdrv_is_inserted(bs)) { then we continue to ret = bdrv_pread(bs, 0, buf, sizeof(buf)); which fails with an error. So this patch is basically to prevent find_image_format() from trying to read from a blank disk. Maybe there is a better way to do this? regards ronnie sahlberg