Jakoblog ...home of jpetso

It all started when I upgraded to the new Kubuntu 8.10, a.k.a. "Intrepid", which did a bunch of nice things to my laptop - most importantly, it resurrected my beloved suspend-to-RAM that went out of order in Hardy. I couldn't be more grateful for that. Intrepid even made the volume keys work... yay!

Of course, every Kubuntu update has its downsides as well. This time, the Wrath of Shuttleworth manifested as a series of interrelated X.org issues: stuttering videos (which played perfectly fine in Hardy), mouse cursor jumps once I keep the mouse quiet for a few seconds, and a curious lack of autoconfiguration for the VGA output - something that had mysteriously worked since the previous release, so I had not questioned it despite knowing that Xrandr 1.2 was not the most enthusiastically hyped area of KDE development known to mankind.

Not possessing or even requiring a projector or external monitor by myself, I was able to live with this for a month or so. But when I had to borrow a collegue's laptop for a university presentation last Friday - after not getting my own machine to spit out proper signals - the Time of Change had come. (And no, I don't mean a certain KDE release with that codename.) On that day, I was torn between no VGA output at all on the one hand, and resolution mismatch problems on the other hand. Neither did I know how this stuff even works, nor that I could have easily solved all of this with a few simple calls to the xrandr command line utility.

I had to get my VGA output working though, because this Tuesday I would throw a movie night at my place, with a nice projector borrowed from my parents, lighting the White Wall of Moving Pictures. I needed to get rid of both the playback stutter and the projector output uglyness. Step by step, I got to the root of all evil.

First step: Figuring out the bad guy. With Google as my weapon of choice, an Ubuntu forum thread about the playback stutter issue was to be found, strengthening my hopes of not suffering alone. The solution of switching to Fluxbox or GNOME is not one of my favorite plans though, but at least it helped determine that KWin is innocent (by making it work in a Fluxbox session, but not with Compiz in a KDE session). Another thread pointed out the amazing correlation between mouse jumps and video stutter.

So while writing all of this up in a bug report, I remembered a blog entry by nixternal pointing out that the "Detecting RANDR (monitor) changes" kded service (to be found in System Settings) was causing problems for people with external monitors. In a stroke of luck, disabling that service was indeed enough to get rid of both the stutter and the jumps. Terrific.

But I still had to get the connection with my projector to work. So I immersed myself in the skillful use of the xrandr command line utility, and went on a search for the 10-second timer that messed up not only my system but that of countless others as well. Turns out that the "Detecting RANDR (monitor) changes" service is not even a part of KDE proper - it's a semi-private branch of krandr by KWin maintainer Lubos Lunak. The thing that causes my video to stutter, my mouse to jump, but also causes other monitors to flicker or recalibrate: all of that is caused by recurring polling of X, in order to notice when external video outputs are connected. (Certain hardware is not able to notify applications in certain scenarios, so that polling would have been ok if it didn't cause havoc on so many systems.)

Second step: getting it all to work! For my movie night, the combination of disabled kded service and xrandr fuzzing was sufficient to get the film nicely rolling. However, it was a slight disappointment that KDE's own display configuration in System Settings ("Size & Orientation", a.k.a. krandr) failed so ungracefully. When it started up, it automatically switched my laptop screen ("LVDS") to some weird resolution (1360x768, I believe), and not for the Love of God would it enable the projector output ("VGA"). All of this while the seemingly trivial xrandr command line tool achieved those tasks rather nicely.

Needless to say, I wasted another day with diving into the krandr code, and fixing one issue after the other. So the net gain for you, dear reader, will be a System Settings screen configuration tool in KDE 4.2 that Mostly Works (TM). Unthinkable joy shall be your reward for reading this crap all the way down! Congrats for your persistence. Dual-monitor setups? Nope, sorry. But reliable mode switching that doesn't make you go OMG WTF BBQ and doesn't mess up your screens if you merely start it. That is what you'll get.

I also hope that Kubuntu will soon update to the 7-week-old latest revision of that notorious "Detecting RANDR (monitor) changes" service, because that version already (already?) has the 10-second fuck-up timer disabled. I only would have hoped that the merging of unreleased hacks into the default setups of every Kubuntu user out there was not taken so lightly, but hey - I still haven't switched to Fedora or OpenSUSE so it can't be that bad. (...right?)

Third step: getting to know the latest trends. Seems like Plasma in 4.2 will feature a new screen management library called kephal, which is going to replace krandr in the near future. Chances are KDE and Plasma get decent multi-head support soon, but that's not quite my area of expertise - I'm just the occasional janitor, whereas Aike or Aaron have a much better grasp what the future holds for the neverending construction site that is screen management. Personally, I'm looking forward to getting my now-working configuration tool not broken until the next Surge of Technology sweeps through the lands of X.org.