[SLOF] [PATCH] vio-vscsi: Support multiple channels / buses

Thomas Huth thuth at redhat.com
Thu Jan 10 17:21:16 AEDT 2019

On 2019-01-10 00:59, Alexey Kardashevskiy wrote:
> On 10/01/2019 04:05, Thomas Huth wrote:
>> The spapr-vscsi device of QEMU supports multiple channels (a.k.a. buses).
> What about virtio-scsi?

While in hw/scsi/spapr_vscsi.c you can find ".max_channel = 7", virtio-scsi
in QEMU does not have these channels:

$ grep -r VIRTIO_SCSI_MAX_CHANNEL include hw
include/hw/virtio/virtio-scsi.h:#define VIRTIO_SCSI_MAX_CHANNEL 0
hw/scsi/virtio-scsi.c:    virtio_stw_p(vdev, &scsiconf->max_channel, VIRTIO_SCSI_MAX_CHANNEL);
hw/scsi/virtio-scsi.c:    .max_channel = VIRTIO_SCSI_MAX_CHANNEL,

And in the virtio spec:

"When used to address a target and logical unit, the only supported format for lun is: first byte set to 1,
second byte set to target, third and fourth byte representing a single level LUN structure, followed by four
zero bytes.

According to SAM5, "single level LUN" means no bus or channel or whatsoever.


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