ci/lava: Start Xorg on request, for Piglit

We will need this for running Piglit jobs.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Acked-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10139>

.gitlab-ci/lava.yml.jinja2

@@ -112,7 +112,23 @@ actions:
           - export PIGLIT_REPLAY_DEVICE_NAME=gl-{{ gpu_version }}
           - export PIGLIT_RESULTS={{ gpu_version }}-${PIGLIT_PROFILES}
 
-          - export LIBGL_DRIVERS_PATH=`pwd`/install/lib/dri
+          - export LIBGL_DRIVERS_PATH=/install/lib/dri
+
+          # If we want Xorg to be running for the test, then we start it up before the
+          # LAVA_TEST_SCRIPT because we need to use xinit to start X (otherwise
+          # without using -displayfd you can race with Xorg's startup), but xinit will eat
+          # your client's return code
+          - "if [ -n $LAVA_START_XORG ]; then
+               echo 'touch /xorg-started; sleep 100000' > /xorg-script;
+               env LD_LIBRARY_PATH=/install/lib/ xinit /bin/sh /xorg-script -- /usr/bin/Xorg -noreset -dpms -logfile /Xorg.0.log &
+               for i in 1 2 3 4 5; do
+                 if [ -e /xorg-started ]; then
+                   break;
+                 fi;
+                 sleep 5;
+               done;
+               export DISPLAY=:0;
+             fi"
 
           - "if sh $LAVA_TEST_SCRIPT; then
                   export RESULT=pass;