[libvirt] [Qemu-devel] [PATCH 2/3] scsi-disk: Add device_id property

[Markus Armbruster]

Kevin Wolf <kwolf at redhat.com> writes:

> Am 28.01.2019 um 09:50 hat Peter Krempa geschrieben:
[...]
>> 2) Is actually using 'scsi-cd'/'scsi-hd' the better option than
>> 'scsi-disk'?
>
> Yes, scsi-disk is a legacy device. Maybe we should formally deprecate
> it.

There's an internal use in scsi_bus_legacy_add_drive(), which in turn
powers two legacy features:

1. -drive if=scsi

   Creates scsi-disk frontends.

   Only works with onboard HBAs since commit 14545097267, v2.12.0.

2. -device usb-storage

   Bad magic: usb-storage pretends to be a block device, but it's really
   a SCSI bus that can serve only a single device, which it creates
   automatically.

If we deprecate scsi-disk, we should deprecate these, too.  Can't say
whether that's practical right now.

>> 3) Since upstream libvirt supports qemu-1.5 and newer and 'scsi-cd' is
>> already supported there, can we assume that all newer versions support
>> it? (Basically the question is whether it can be compiled out by
>> upstream means).
>
> I think so.

Compiling out scsi-hd or scsi-cd, but not scsi-disk would be silly.  All
three devices are in scsi-disk.c.  You'd have to hack that up to be
silly.