[Bug 1502884] Re: Super important feature req: QEMU VNC server: Introduce a keyboard "norepeat" option!

From: Daniel Berrange <1502884@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1502884] Re: Super important feature req: QEMU VNC server: Introduce a keyboard "norepeat" option!
Date: Mon, 28 Sep 2020 08:15:14 -0000	[thread overview]
Message-ID: <160128091428.9920.14889627074354651084.malone@chaenomeles.canonical.com> (raw)
In-Reply-To: 20151005123157.4012.27683.malonedeb@soybean.canonical.com

The VNC server doesn't get involved in key repeat functionality, it just
passes keys from the client onto the guest OS.  The client can indicate
that it is doing key repeat by sending a series of "key down" events,
and only 1 "key up" event to indicate end of auto-repeat. The guest OS
can itself implement auto-repeat at any frequency it wishes by watching
the key stream. The "-norepeat" option to X11 VNC that is referred to
here isn't something related to the VNC part of x11vnc, but rather it
appears related to the X11 part which corresponds to the guest OS in
QEMU's case. I don't see there is much QEMU can do here.

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https://bugs.launchpad.net/bugs/1502884

Title:
  Super important feature req: QEMU VNC server: Introduce a keyboard
  "norepeat" option!

Status in QEMU:
  New

Bug description:
  Hi,

  A big issue when using QEMU's VNC server (VNC KVM) is that, when
  there's a network lag, unintended keypresses go through to the QEMU
  guest VM.

  This is frequently "enter" keypresses, causing all kinds of unintended
  consequences in the VM. So basically it's extremely dangerous.

  This is because the VNC protocol's keyboard interaction is implemented
  in terms of key down - key up events, making the server's keyboard
  autorepeat kick in when it should not.

  For this reason, it would be great if QEMU's VNC server part would be enhanced with an option such that when a VNC protocol key down is received, then locally that is treated as one single keypress only (I don't know how that should be implemented but I guess either as an immediate key down - key up sequence locally, or key down + key up after say 0.05 seconds), instead of waiting for the key up event from the VNC client.

  Thanks!

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