weston on i915

[Erwin Rol]

Hello All,

I have wayland/weston running on several embedded systems and now
updated from weston 4.0 to weston 5.0 and that caused a problem on my
oldest hardware with a Intel N270 Atom and 945GSE "gpu" that use the
Mesa i915 driver. I have other systems with more modern gpu that use
the i965 driver and those work fine.

Weston on the old 945 complains with;

[02:52:17.426] failed to create gbm surface
[02:52:17.426] Failed to init output gl state
[02:52:17.426] Enabling output "LVDS-1" failed.
[02:52:17.426] Error: cannot enable output 'LVDS-1' without heads.

After looking where that msg was in the code I noticed the
HAVE_GBM_MODIFIERS define. 

That define is set when the following configure.ac code;

  PKG_CHECK_MODULES(DRM_COMPOSITOR_GBM_MODIFIERS, [gbm >= 17.1],
                    [AC_DEFINE([HAVE_GBM_MODIFIERS], 1, [GBM supports modifiers])],
                    [AC_MSG_WARN([GBM does not support modifiers])])

To test I just removed that and rebuild everything.

And than things work again.

Now the question, is just checking for gbm >= 17.1 good enough to see
if gbm modifiers are supported? Or is there something else wrong ?

Any hints would be welcome. 

TIA,

Erwin