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21:56 - Debian/X.org notes - Xserver 1.6, Intel 2.6.1, ... what's up in XSF?

It has been a while since my last post here. Not because nothing happened, but mostly because I did not have time to do much for X. Fortunately, Julien is taking good care of X in Debian so we are still close to latest upstream bits. Obviously, due to Lenny's freeze, everything is happening in experimental these days.

Xserver 1.6

The release Xserver 1.6 is expected in the near future. 1.6-rc1 (1.5.99.901) entered experimental recently. Both video and input driver ABIs changed and very few drivers have been rebuilt so far. So if you're not running Intel or Radeon, you might not be able to upgrade yet. Please be patient :) You might have heard that many things are happening in X.org these days: DRI2, kernel-modesetting (KMS), RandR 1.3, ... Everything is not ready yet, but it's getting close for real.

Radeon 6.10.0 and Intel 2.6.1

Radeon driver 6.10.0 was released in early 2009. As usual, it brings many fixes, and improvements for modern boards (see Alex Deucher's blog for details). However, Radeon is not ready for above DRI2 and KMS yet. Most of the development for these new features is first done in the Intel driver, which got recently bumped to 2.6.1 as well.

DRI2

DRI2 is the new Direct Rendering Infrastructure. The most noticeable change from the user point of view is support for Redirect Direct Rendering, which basically means that your 3D application can be wobbly/transparent in Compiz. See Kristian Høgsberg's blog for details.

If you want to try DRI2 on Intel, you have to enable UXA as the acceleration architecture in xorg.conf (Option "AccelMethod" "UXA" in the Device section). DRI2 will then be enabled automatically. Then, it may or may not work, depending for instance on the hardware. I get a black screen at startup on i865 while i945 works fine until I start Compiz (the server suddenly exits for some reason then). Note that you probably want to upgrade your Mesa packages to experimental as well here (7.3 has been released recently). Of course, running git snapshot of various components (Mesa, libdrm, kernel drm, Intel driver, ...) may help since the released versions seem to not be entirely ready yet. But, things should may be ready to use for everybody in the near future.

Kernel Modesetting

The other nice feature that makes a lot of noise in X.org these days is Kernel modesetting (KMS). It moves the management of mode (aka resolution+rate) into the kernel. It helps support for switching between different users' sessions, enables reporting of kernel messages (oops, panics, ...) while X is running, and reduces the need to blank the screen during boot (since the kernel can setup the display early and X doesn't have to change it later independently).

KMS testing requires a bleeding-edge kernel (2.6.29). Using a git snapshot of the drm stack is probably a good idea as well since I couldn't get KMS to work on 2.6.29-rc2 here. Again only Intel will support KMS soon, but other drivers will follow.

Panning is back (aka RandR 1.3)

Xserver 1.6 brings support for the 1.3 version of the RandR X extension. Among other improvements, it reintroduces one feature that many users miss since it was removed back in Xserver 1.3 or so. "Panning" (often referred to as "Virtual Desktop") gives the ability to move the display within a larger screen when the mouse approaches from the border. Instead of being configured with the Virtual option in xorg.conf (this option means something else nowadays), it may now be enabled/tuned with xrandr --panning. You'll need the latest libxrandr2 and xrandr utilities to do so (the latter is not uploaded yet).