Xmir: xrandr outputs information is lost after root window resize

[Daniel van Vugt]

[Impact]

Users trying to use xrandr on Xmir will get bogus info for the attached displays after resizing the root window.

[Test Case]

1. Start up an X application through Xmir.
2. Type xrandr and observe output.
3. Resize the window.
4. Type xrandr again.

Valid output should be given.

[Regression Potential]

None observed.

--------------------------------------------
Original Description:
Xmir: xrandr outputs information is lost after root window resize (non-rootless mode)

$ xrandr
Screen 0: minimum 320 x 200, current 1920 x 1200, maximum 32767 x 32767
VGA-0 disconnected
DP-0 disconnected
HDMI-0 disconnected
DP-1 disconnected
HDMI-1 disconnected
DP-2 connected 1920x1200+0+0 520mm x 320mm
   1920x1200@60.0Hz 59.88*+
DP-3 disconnected

# Now I resize the root window in the Mir shell...

$ xrandr
Screen 0: minimum 320 x 200, current 1631 x 1098, maximum 32767 x 32767

[Daniel van Vugt (vanvugt)]

Hmm, seems to be a feature actually...

   if (!xmir_screen->windowed) {
        xmir_screen->windowed = 1;

[Daniel van Vugt (vanvugt)]

Reopened. If Unity8 is resizing Xmir then we'll hit this bug (which is usually harmless) however some sensitive apps might then fail to start -> bug 1602561

[Daniel van Vugt (vanvugt)]

The issue is the code says it's inserting a fake output to replace the old ones, but no code has ever existed to actually do that :)

    if (!xmir_screen->windowed) {
        xmir_screen->windowed = 1;

        XMIR_DEBUG(("Root resized, removing all outputs and inserting fake output\n"));

        while (!xorg_list_is_empty(&xmir_screen->output_list)) {
            struct xmir_output *xmir_output = xorg_list_first_entry(&xmir_screen->output_list, typeof(*xmir_output), link);

            RRCrtcDestroy(xmir_output->randr_crtc);
            RROutputDestroy(xmir_output->randr_output);
            xmir_output_destroy(xmir_output);
        }
    }

[Daniel van Vugt (vanvugt)]

https://git.launchpad.net/~xmir-team/xorg-server/+git/xmir/commit/?id=d19641fc01f77420b4ec5d6db6723f519f8f8272

[Launchpad Janitor (janitor)]

This bug was fixed in the package xorg-server - 2:1.18.4-1ubuntu3

---------------
xorg-server (2:1.18.4-1ubuntu3) yakkety; urgency=medium

  * debian/patches/xmir.patch:
    - Fix bottom/right edge corruption. (LP: #1510849)
    - Fix key repeat. (LP: #1591356)
    - Don't delete outputs without replacing them. (LP: #1504422) (LP: #1602561)
    - Xmir -debug: Log WM types by name and number.
    - Implement fake GLX frame notification/timing.
    - Improve focus tracking.

 -- Robert Ancell <email address hidden> Thu, 21 Jul 2016 11:42:03 +0200