Comment 9 for bug 1504387

I don't think you mean GL_EXT_abgr, I don't see Weston using that.

Weston is using GL_BGRA_EXT format, when GL_EXT_texture_format_BGRA8888 extension is available. Weston's GL-renderer refuses to start without this extension.

I believe this is because GL_BGRA_EXT, GL_UNSIGNED_BYTE matches the WL_SHM_FORMAT_XRGB8888 and WL_SHM_FORMAT_ARGB8888 layouts, so we can avoid a conversion.