Pasky’s Log

Just a quick note for those googlers out there again. My sister has my old and trusty Radeon 7000 (RV100) GPU in her machine and after distro upgrade, we had trouble getting it working with respectable performance; DRI etc. was all fine after the usual installation round of firmware-linux, but heavy 2D blipping work (e.g. moving windows, OpenTTD, darkening/lightening whole screen in various applications) was taking awful amounts of CPU within Xorg and things were really choppy.

It seems that there are some bugs lurking within the KMS; radeon.modeset=0 on the kernel commandline has a good shot at curing things like this!

At our university department, we have a reasonably large deployment of Debian installations that are all (almost) the same software-wise, but quite diverse hardware-wise (we buy few new computers each year, and get rid of the oldest ones). Our users are fairly conservative (except wrt. the ‘ida’ package, for some reason) and we have quite a few local tweaks, so even though these are desktop machines, we follow Debian stable and it’s ideal for us – it takes us quite long to test, tweak and debug new release before an upgrade.

Of course, there is a catch – new computers have graphic cards that lenny simply cannot cope with anymore. And if you want new drivers, you need new xorg version. There are no official backports. So you are faced with installing xorg from testing (squeeze), but this is a fairly large-scale operation: your libc6 package and other base libraries will be upgraded, your keyboard/console configuration will change, etc. Especially the library upgrade is troublesome, since in order to stay binary-compatible across the whole department, we would need to install libc6 etc. from squeeze on *all* our machines. It is not very likely significant breakage of these packages would go through to testing, but there are risks and overally it adds significant overhead to the task.

Thankfully, there is a neat alternative solution – add Ubuntu to the repository cauldron! Ubuntu Jaunty is very similar to Debian Lenny package-wise, and in fact not even libc upgrade is necessary. Only a fairly isolated set of xorg-related packages will be upgraded, which seems ideal for the purpose.

First, we need to add extra repositories to our Debian stable system. We will need both jaunty and squeeze – this is a mystery, AFAICT no packages from squeeze are being installed during the process, but the squeeze repository is needed for APT to figure out the upgrade path.

Make sure you will stay in stable on general – add this to /etc/apt/apt.conf (create it if necessary):

APT::Default-Release "stable";

Add this to /etc/apt/sources.list:

deb http://ftp.cz.debian.org/debian/ squeeze main non-free contrib                                                                 
deb-src http://ftp.cz.debian.org/debian/ squeeze main non-free contrib                                                             
                                                                                                                                           
deb http://archive.ubuntu.com/ubuntu/ jaunty main restricted                                                                       
deb-src http://archive.ubuntu.com/ubuntu/ jaunty main restricted                                                                   

Not to worry, apt will keep operating on stable unless you explicitly tell it otherwise. Which we shall do right now:

apt-get install -t jaunty xserver-xorg-video-ati xserver-xorg-video-radeonhd \
  xserver-xorg-video-all xserver-xorg-input-kbd xserver-xorg-input-mouse \
  xserver-xorg

This set of packages is crafted for our installations and so that APT allows the upgrade, you will perhaps need to tweak it slightly; you certainly will want to add more input drivers if you are doing this on a notebook. We mess with the input packages since xserver-xorg-input-wacom would pull in newer libc6 package. Carefully review the installation proposal before agreeing to it, of course. Voila, you should have new X.org version with current video drivers on your system now!

Perhaps if we were starting from scratch, Ubuntu LTS releases would be a good option to consider since they keep hardware support up-to-date. However, moving to Ubuntu nowadays would be tedious, and we don’t like various Ubuntu fancy desktop stuff, being conservative UNIXy persons.

Very long time ago, several UCW sages congregated on the ultimate Czech programmer layout – they ended up with a US keyboard just like usual, except that capslock doesn’t lock case (good in itself!) but acts as a second shift, adding diacritic mark on the letter. So caps+s produces Å¡, caps+e produces é and caps+w produces Ä›. I have been using that ever since, but when moving to another system, setting this up always was a bit of a challenge.

But currently, the X11 Czech ucw layout is easy to set up on squeeze/sid (I’m currently using squeeze with xorg from sid – works fine). Xorg keyboard configuration is HAL-driven on sid currently, what you need to do is put this to /etc/default/console-setup:

XKBLAYOUT="us,cz"
XKBVARIANT=",ucw"
XKBOPTIONS="grp:caps_switch"

(Though, the way this works, using two groups, I’m not quite sure how to add another layout with reasonably seamless switching. Not my problem, but some other users might want that.)