'Twas brillig, and Colin Guthrie at 27/08/11 00:46 did gyre and gimble: > Hi, > > OK, so this combo is currently broken! > > Here is the explanation. > > With udev 172, udev-acl would apply ACLs to devices (such as the DRI > device) when console-kit registers a new session. > > This included the gdm user at the login manager. > > systemd is gradually taking over the job of consolekit. This means that > systemd now handles the ACL writing and login sessions should be > visiible via systemctl-loginctl (as opposed to ck-list-sessions). > > > With udev 172, both systemd and console-kit would trigger ACL writes. > Normally this is fine, they both ultimately do the same thing. > > But, it seems that in actual fact, systemctl-logind wasn't ever > registering the gdm session. Thankfully console-kit did, and thus gdm > user got the ACLs it needed. > > > Now this is where the problem arises. With udev 173, udev-acl knows > whether or not systemd is running and if it is, it it won't write the > ACLs. This means that even tho' gdm is still registered with > console-kit, this will never actually trigger an ACL write. > > This means that gdm does not have access to /dev/dri/card0 and thus > cannot determine if the device is capable of 3D accel. This then sets an > atom on the root window which the gnome-session-check-accelerated binary > looks for. This atom acts as a little cache. If it doesn't exist, it > does a full probe and then writes the atom. The next time it runs it > finds the atom and skips the actual checks. But as the atom was written > by gdm when it couldn't access dri, it says no accel is available, even > although the user can actually access it. > > > I've not yet sussed out gdm is not registering with systemd... it should > all be automatic via pam... but something somewhere is failing :s
OK, sussed it out eventually (I was looking in fedora's "master" branch rather than "f16" branch so missed some patches :() gdm patched to make it all work now. I'm not really sure how kdm will behave but I wouldn't be surprised if it's broken. Col -- Colin Guthrie mageia(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mageia Contributor [http://www.mageia.org/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
