Comment # 12 on bug 1201474 from Michal Suchanek

(In reply to Stefan Dirsch from comment #10)
> (In reply to Michal Suchanek from comment #8)
> > but you do need a GL driver to be able to make use of libGLESv2, right?
> 
> (in case that's not a rhetorical question) I would think so, yes. So should
> Mesa-dri be required by libglvnd? I'm not sure, whether that's a good idea.
> Mesa buildrequires libglvnd and I'm anxious to produce a buildloop when
> letting libglvnd require Mesa-dri, which is a subpackage of Mesa.

X11 also depends on video and input drivers, and they in turn need X11 to
build, right?

This is basically the same situation. You have a device-independent GL
infrastructure but you need a device driver for it to work.