Somewhere between the debut of Ubuntu 9.10 (Karmic Koala for those into animal names) and today, the developers/maintainers/overlords of what many consider the leading Linux distribution have fixed the dreaded "kernel mode setting bug" that rendered the X Window system on many computers using Intel video hardware unusable until kernel mode setting was turned off.

There was a talk last week at LinuxTag in Berlin by Egbert Eich about kernel mode-setting and the DRM (Direct Rendering Manager) graphics stack on Linux. Egbert is, of course, a long-time X developer and openSUSE developer at Novell who was one of the masterminds behind the RadeonHD graphics driver and has worked on various pieces of X over the years.

Kernel mode-setting for Intel graphics hardware can already be found in the mainline Linux kernel and will be included by default in the release of Ubuntu 9.10 later this year.

Kernel mode setting will be enabled by default for Intel-based video cards on Ubuntu 9.10, set to be released in October.  I recently played around with this new feature on a Karmic Koala live CD, and share my results below.

Attention developers: This "improvement" you call kernel mode setting is pretty much a regression for users of my particular video chip, the Intel 830m, and could be equally useless for other Intel video hardware. Do you think that maybe figuring out why kernel mode setting doesn't work in these cases is the thing to do?

The next version of Linux is not only the first to offer the Nouveau KMS graphics driver for NVIDIA graphics hardware, it also comes with a multitude of improvements for the two AMD/ATI and Intel graphics drivers which support Kernel-based Mode Setting (KMS).

While the Intel stack may be improved in Constantine, the ATI support has taken a hit, as users were quick to point out in response to last week's article. In particular, when using the ATI kernel mode-setting driver in Fedora 12 (which is the default for pre-R600 hardware), there is a large performance discrepancy.

The problem itself appear to be in the kernel from version 6.06, 8.04, 8.10, 9.04 and 9.10. 7.xx versions are not affected . This is a serious problem because it could allow full system access among others. Canonical has been recommended as a solution to update the kernel.

Kernel mode setting hasn't been "fixed" for older Intel video, but at least the kernel knows not to turn it on when you're running an i915-type chipset (of which i810 is seemingly a subset). This is how things should have been handled from the beginning. Better late than never.