Re: [libvirt PATCH 0/3] Enable copy/paste for vnc displays

On 3/23/22 4:17 AM, Daniel P. Berrangé wrote: > On Wed, Mar 23, 2022 at 12:01:19PM +0400, Marc-André Lureau wrote: > > Hi > > > > On Wed, Mar 23, 2022 at 12:47 AM Jonathon Jongsma <jjongsma(a)redhat.com&gt; wrote: > > > > > > This patch series enables support for the qemu-vdagent character device which > > > enables copy/paste support between guest and client when using vnc graphics. > > > > > > The guest must be configured with something like the following: > > > > > > <channel type='qemu-vdagent'> > > > <source clipboard='on' mouse='on'/> > > > <target type='virtio' name='com.redhat.spice.0'/> > > > </channel> > > > > > > Copy/paste sync requires a vnc client that has support for copy/paste commands. > > > Currently virt-viewer does not work, but the version of tigervnc provided by > > > fedora (executable name 'vncviewer') does work. > > > > > > More details about this device on Gerd's blog: > > > https://www.kraxel.org/blog/2021/05/qemu-cut-paste/ > > > > > > OPEN QUESTIONS: > > > > > > - I'm not fully convinced that the `<source>` element is the right place for > > > the new `clipboard` / `mouse` configuration options, but I'm not sure that > > > adding a new xml element to the `<channel>` is the right approach either. > > > Suggestions welcome. > > > > I am not convinced <channel> is appropriate either for -chardev > > qemu-vdagent. That's why in my dbus display series it's an > > implementation detail > > (https://patchew.org/Libvirt/20211222194345.766352-1-marcandre.lureau@redh...), > > and it's not exposed to the domain XML directly. However I realize > > that my approach is probably broken, as it looks like I totally missed > > the associated virtserialport! :) > > > > As you say "source" is strange to put those extra channel options too. > > > > And the only really valid associated device is a virtserialport of > > name "com.redhat.spice.0", so what's the point in exposing that detail > > to the user? You could say the same thing about the normal spice vdagent, right? And we allow the user to specify a different virtio name for the spicevmc channel. spice-vdagent does offer a --virtio-serial-port-path option that can be used to connect to a different name within the guest, after all. > > At the QEMU level we have one serial port with chardv > > -chardev qemu-vdagent,id=ch1,name=vdagent,clipboard=on > -device virtio-serial-pci \ > -device virtserialport,chardev=ch1,id=ch1,name=com.redhat.spice.0 > > > but IIUC, we can have multiple frontends - ie both VNC and DBus > display, and in that case the clipboard=on property on the > chardev will apply to both VNC & DBus displays. We can't > control clipboard independantly for the displays, so it is > right to put the control in the XML for the <channel> for > both VNC and DBus. > In addition to <channel>, there are several other xml elements that essentially map to a qemu character device: <serial>, <console>, etc. Would it make more sense to introduce a new element like this for the qemu-vdagent? This might make it easier to introduce new configuration options that wouldn't really fit in the general <channel>. For example, something like: <qemuvdagent> <clipboard copypaste="yes"/> <target type='virtio' name='com.redhat.spice.0'/> </qemuvdagent>