On Tue, Sep 9, 2014 at 8:31 PM, Chun Yan Liu <cy...@suse.com> wrote: > > >>>> On 9/10/2014 at 02:23 AM, in message >>>> <87tx4girg6....@blackfin.pond.sub.org>, > Markus Armbruster <arm...@redhat.com> wrote: >> "Chun Yan Liu" <cy...@suse.com> writes: >> >>>>>> On 9/6/2014 at 05:23 AM, in message >> > <alpine.deb.2.02.1409052202451.2...@kaball.uk.xensource.com>, Stefano >> > Stabellini <stefano.stabell...@eu.citrix.com> wrote: >> >> On Fri, 5 Sep 2014, Chunyan Liu wrote: >> >> > Using xen tools 'xl vncviewer' with tigervnc (default on SLE-12), >> >> > found that: the display of the guest is unexpected while keep >> >> > pressing a key. We expect the same character multiple times, but >> >> > it prints only one time. This happens on a PV guest in text mode. >> >> > >> >> > After debugging, found that tigervnc sends repeated key down events >> >> > in this case, to differentiate from user pressing the same key many >> >> > times. Vnc server only prints the character when it finally receives >> >> > key up event. >> >> >> >> Is this actually how a vnc client should behave? >> >> How do the vnc client and server from realvnc behave in this regard >> >> (they are the reference implementation)? >> > >> > VNC protocol doesn't specify how to handle key repetition. Tightvnc >> > sends key-down&key-up repeatedly, but some example like RealVNC for >> > Windows does the same thing - it sends only repeated key-down. >> > >> > Generally the VNC keyboard handling gives lot of space for interpretation >> > and so the implementations differ. >> >> If implementations differ, and QEMU already behaves like some of them, >> then why change it? > > To change qemu side because we could not expect each VNC client behaves > the same when holding key down, some sending key-down, key-up, key-down, > key-up; but some sending key-down, key-down, key-down .... Without change, > client only sending key-down, key-up, key-down,key-up ... can get correct > display.
The VNC keyboard handling is pretty straight forward. The keys sent are symbolic and correspond to input events (as interpreted by an application). Whether you get repeat events depends on a lot of client side configuration. >> What exactly gets fixed and what gets broken by the >> proposed change? > > Holding the key down, only one character is printed, but repeated characters > are expected. Happens on some vnc client. Either vnc client or vnc server > should change some to match. You should fix TigerVNC. It's broken if it isn't sending repeat events. Regards, Anthony Liguori >> >> [...] >> >> > > >
