Jocelyn, >> How can I check for sure whether I am using 24 or 32 bits per pixel >> ? > > The easiest solution if you already rebuilt your kernel is to print > the variable bpp here: > > https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/mgag200/mgag200_mode.c#L326 > > pr_info("mgag200 bpp %d\n", bpp); Did that, and I get "mgag200 bpp 32". > Also if you can run Wayland at 1440x900@60, that would mean the > hardware is indeed able to handle it in 32bit. I can indeed run Wayland at 1440x900@60. So I think I'm right in saying that my graphics chip can handle 1440x900@60 with 32 bits per pixel. However, while searching /var/log/messages for the bpp output above, I also found these two lines: /usr/libexec/gdm-x-session[2366]: (==) modeset(0): Depth 24, (==) framebuffer bpp 32 /usr/libexec/gdm-x-session[2366]: (==) modeset(0): RGB weight 888 in case it makes a difference. Thanks, Roger.