https://bugs.freedesktop.org/show_bug.cgi?id=40790
--- Comment #9 from Nicholas Miell nmiell@gmail.com 2011-09-24 23:17:00 PDT --- OK, startx + .xinitrc wasn't initializing a ConsoleKit session, so my account wasn't getting added to the ACL on /dev/dri/card0 and piglit was running on indirect GLX.
Having sorted that out, the BadDrawable errors are gone, the basic test is passing, and the readPixSanity test is failing in the same way as the "updated results" attachment.