GAMMA_LUT sizes other than 1024 cause a crash during startup if the memcpy()
calls in xf86RandR12CrtcSetGamma() read past the end of the legacy X11 /
XVidMode gamma ramp.
This is a problem on Intel ICL / GEN11 platforms because they report a GAMMA_LUT
size of 262145. Since it's not clear that the modesetting driver will generate a
proper gamma ramp at that size even if xf86RandR12CrtcSetGamma() is fixed, just
disable use of GAMMA_LUT for sizes other than 1024 for now. This will cause the
modesetting driver to disable the CTM property and fall back to the legacy gamma
LUT.
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Fixes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1193
Tested-by: Mark Herbert
617f591fc4