(In reply to magiblot from comment #14)
> Created attachment 143267 [details]
> Stderr output of weston when run on i915 (with patch from comment #13)
> 
> (In reply to Daniel Stone from comment #13)
> 
> Thank you very much! I applied the patch over weston-git and tried again. It
> got closer, but still doesn't work for me.
> 
> The following errors have now appeared:
> 
> > [13:53:34.450] failed to create kms fb: No such file or directory
> > [13:53:34.450] failed to get drm_fb for bo
> > [13:53:34.979] failed to create kms fb: No such file or directory
> > [13:53:34.980] failed to get drm_fb for bo
> > [13:53:35.035] failed to create kms fb: No such file or directory
> > [13:53:35.035] failed to get drm_fb for bo
> 
> weston doesn't crash or anything. After startup, the content of the tty
> continues being shown and weston appears to be idle. Ctrl+Alt+Backspace
> exits weston normally and control is given back to the shell.
> 
> Cheers.

If you add #undef HAVE_GBM_MODIFIERS into libweston/compositor-drm.c and
rebuild, it should do as a temporary hack.