Comment 59 for bug 508699

Did a lot of additional tests with "plain vanilla" kernels from kernel.org: none of the 2.6.32-kernels work (2.6.32, 2.6.32.1, 2.6.32.2, ..., 2.6.32.11). All of them are broken on certain hardware. All show the same behavior: if once booted with a working kernel, then rebooting with one of the 2.6.32-series will make X11 work, as far as memory isn't wiped in between.
All Ubuntu-kernels I could find within archives show same behavior: they work, as far as a working kernel was booted before (linux-image-2.6.32-15-generic, linux-image-2.6.32-16-generic, linux-image-2.6.32-19-generic).

Kernel 2.6.31.13 works, as does 2.6.31.12. The Ubuntu-kernel linux-image-2.6.31-21-generic (linux-image-2.6.31-21-generic_2.6.31-21.59_amd64.deb) works too, regardless what state the system was in before.

Kernel series 2.6.33 have some really crucial behavior: booted after switching from a working kernel these do not allow to change resolution! The only resolution seen is the one the system ran at before! If powered on only resolutions up to 800x600 are available. From time to time the system just stops responding, but only if powered on. A hard reset is necessary to make it work again. What exactly caused these "hangs" I was not able to find out, because there are no log or dmesg-entries which could shade some light on it.

Kernel 2.6.34-rc3 works again as 2.6.31.13, 2.6.31.12 and linux-image-2.6.31-21-generic did. Regardless of the state the system was in before.

I am using kernel 2.6.34-rc3 from kernel.org at the moment.