Re: [Qemu-devel] [PATCH 3/3] qemu-iotests: 140: use virtio-scsi instead of IDE

[Max Reitz <mreitz@redhat.com>]

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On 10.02.2016 20:26, Sascha Silbe wrote:
> Dear Max,
> 
> Max Reitz <mreitz@redhat.com> writes:
> 
> [tests/qemu-iotests/140]
>>> -_launch_qemu -drive if=ide,media=cdrom,id=drv,file="$TEST_IMG",format=$IMGFMT \
>>> -    2> >(_filter_nbd)
>>> +_launch_qemu -drive if=none,media=cdrom,id=drv,file="$TEST_IMG",format=$IMGFMT \
>>> +    -device virtio-scsi -device scsi-cd,drive=drv 2> >(_filter_nbd)
>>
>> Why not just omit the device (and the media=cdrom along with it, keeping
>> if=none)? This will change the reference output because there is no
>> longer any tray to be moved, but this will still test what it's supposed to.
>>
>> (This may sound hypocritical coming from me, because I wrote this test
>> so I could have just done so in the first place; I guess I just didn't
>> realize that 'eject' works on device-less drives, too.)
> 
> Is this supposed to work? I.e. can we rely on it?

Let's say I would rely on it. :-) (which is why I proposed it)

The test checks that ejecting a BlockDriverState tree from a
BlockBackend (that is, a medium from a drive) works even if that
BlockBackend is exposed via an NBD server. It doesn't really matter
whether the drive has a device or not, the main thing is that the NBD
server notices that the medium is ejected and automatically stops
offering the drive.

So I would think that we are supposed to be able to rely on it; if we
cannot, something else is probably broken.

>                                                   If so, that would
> certainly be the easier route for this particular test. Test coverage
> should be unaffected as 139 already tests ejection (using virtio, unlike
> 118 which is PC-only).
> 
> The aliases patch has a value of its own, but that's a separate
> matter.

Yes, certainly.

Max


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