Pete Zaitcev (zaitcev) wrote,
Pete Zaitcev
zaitcev

Xen: Absolute pointer, Jitters

On the absolute front, I got xenpv working, but its performance is awful, exactly the same as evdev's. Cursor position does not match, and motion is not just jumpy, but it's back-and-forth jumpy. And I think I know what the reason is:

(==) ServerLayout "Default Layout"
(**) |-->Screen "Screen0" (0)
(**) |   |-->Monitor ""
(**) |   |-->Device "Videocard0"
(WW) No monitor specified for screen "Screen0".
        Using a default monitor configuration.
(**) |-->Input Device "Keyboard0"
(**) |-->Input Device "VMouse0"
(II) No default mouse found, adding one
(**) |-->Input Device "<default pointer>"

The two input devices fight for sending the events and thus the jitters.

The evdev suffers from exactly the same problem, so I can't just steal code from it. Tomorrow is time for "grep -r 'No default mouse found'".

I'm sure that this problem is possible to work around in xorg.conf. Otherwise, nobody would have been able to use evdev for input (it's just that bad), and I am sure Stone, Hoksberg, or whoever actually test the thing. However, this is not desirable. I prefer xenpv to be a drop-in replacement for mouse for now.

This also may be not worth fighting, because, as I mentioned before, Katz wants mouse itself to support absolute input, in the same way vmmouse does it now. This way, none of our configuration tools would need any changes. So hmm.... Anyway, tomorrow.

P.S. Hackery of X is very much fun, I should've done it before.

{Update: O.M.G.}

Tags: linux, x11, xen
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