[Spice-devel] [spice-gtk v4 00/13] CD sharing feature

[Yuri Benditovich]

Hi

On Thu, Sep 20, 2018 at 8:59 AM, Gerd Hoffmann <kraxel at redhat.com> wrote:

>   Hi,
>
> > spice-server changes were backward-incompatible and were not accepted
>
> Why they are not backward compatible?
>

Possible, Marc Andre can answer. He was involved at time
of presentation of 2 solutions and did not raise any objections.


>
> > usb-storage is just a header processing and holder of units
>
> Yes, bulk-only transport isn't that difficuilt to handle.
>
> > scsi source is 2K lines, similar to nbd server
>
> Probably the bare minimum needed to get things going.
> Which guests have you tested with this?
>

Several Windows + several Linuxes. What you recommend to add to the check
list?


> Be prepared that this will become larger over time,
> if you find that guests submit scsi commands which
> you do not emulate.
>
>
Of course, but the MMC spec has mandatory and optional features.
All the mandatory ones implemented.
At time of writing scsi processing we tried to find some shared code
that can be used, but failed to find suitable.


> > nbd requires also code for nbd channel
>
> Sure, but should be mostly glue code binding the
> existing pieces together.
>
> > > Yes.  But why is this a problem?  If the user can share one (or maybe
> > > two for both installer and driver) iso images, having that many cdrom
> > > drives in the guest should not cause much confusion, no?
>
> > And if the user does not want to share anything? Why he/she must have
> these
> > drives?
>
> Well, physical computers have cdroms built in too.  And they are
> likewise there even if not used.  I fail to see why this is a problem.
>

If I'm not mistaken, the boot screen in this case will be like one on
attached bitmap.
This is definitely not a feature, correct?


>
> > With usb redirection the number of emulated drives on single channel
> > is potentially unlimited (using multi-unit device)
>
> No, the limit is 16 LUNs for bulk-only transport.  Should be enough
> though, I have a hard time to imagine use cases where you need more
> than 2-3 isos.
>
> Note that you can't hotplug the LUNs individually.
>

There are several possible solutions for hot-plug 'removal' scenario,
but due to time constrains we still did not select preferred one
and this is the reason why we do not enable multiple units per device right
now.
Real removal of individual unit can be done only when we stop redirecting
it.


>
> cheers,
>   Gerd
>
> Thanks,
Yuri
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