Re: Half a usb-redir idea

["Marc-André Lureau" <marcandre.lureau@gmail.com>]

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Hi

On Tue, Mar 16, 2021 at 11:33 PM Dr. David Alan Gilbert <dgilbert@redhat.com>
wrote:

> * Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
> > On 3/16/21 6:21 PM, Dr. David Alan Gilbert wrote:
> > > Hi,
> > >   I've got a half-baked idea, which I thought might be worth
> mentioning.
> > >
> > > How hard would it be to give qemu a usbredir server rather than client?
> > > It would have nothing guest visible but would look logically like the
> > > front (?) half of a usb interface; then you could use all of the
> > > existing qemu emulated and passthrough device code, to build a usb
> > > hierarchy and present it to a remote qemu.
> > >
> > > You'd get the ability to do emulated USB CDROM/storage, audio, network
> > > and the glue for host USB connection (and smart cards??) - all in one
> > > client that you can then use for connecting to a remote qemu.
> > >
> > > The next step of that is to make something analogous to a
> > > qemu-storage-daemon, but for USB, so you have something that can
> > > do all that USB stuff without actually having any processors.
> > >
> > > The even crazier step would then be to add a VNC client, and then you
> > > have an almost complete remote client.
> >
> > Similarly to the out-of-process feature (on the same host)?
> > Are you also interested in remote use (different host)?
>
> I was mainly interested in it for remote access; but potentially this
> provides a clean break point to move all of the USB device emulation
> into one separate process.
>
>
It's an idea I suggested a few times too, once at least during 2017 KVM
Forum multi-process talk, & when it was decided to implement usb CD
emulation in spice-gtk (which I wish would use existing qemu code instead,
or the NBD server I implemented initially, long time ago..). So yup, I'd
like to see this happen too eventually. However it's not so attractive
imho, you rather want virtio/vhost-user and for other devices you don't
have a choice I'd focus on vfio-user. At some point hopefully, qemu should
be able to provide a usb controller via vfio-user if you need it.

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