Re: vnc clipboard support

[Gerd Hoffmann <kraxel@redhat.com>]

On Tue, Feb 02, 2021 at 11:17:09AM +0000, Daniel P. Berrangé wrote:
> On Tue, Feb 02, 2021 at 12:10:15PM +0100, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > > How do you rate-limit intelligently to avoid overflowing the guest keyboard buffers?
> > > 
> > > Like I said earlier in this thread, this is a big problem with
> > > keyboard injection.
> > 
> > It's a solved problem though, the qemu vnc server has throttling
> > implemented already.  There even is an option to configure the delay
> > (key-delay-ms).
> 
> Depends on your view of "solved" really.

"solved" as in "automated qa can send command lines as vnc key events
way without loosing chars".  That is the use case it was added for.
Doing it in qemu works a bit better and faster than doing it in the vnc
client as you don't have to account for stuff like network delays then.

> If I've highlighted a region
> of text in openoffice that is 100 KB in size, and press "Ctrl-V" in
> the VNC window for the VM, with a 10 ms delay, i'll be waiting 15
> minutes for it to finish injecting keystrokes.

Yep.  It's clearly not for really large quantities of text.

But sending "wget $url" to the guest shell works reasonable well.

> Anything longer than 1 second is unacceptable. If you make the delay
> too short the guest keyboard handler will loose keys. So realistically
> I think keyboard injection is limted to about 100 characters of text.

Yes.

take care,
  Gerd