I wanted to do this a long ago, but a lot of things prevented me from doing it. Yesterday I had many many kernel compile sessions, image restore and reconfiguration. But all of them ended in disk corruption during ubuntu-desktop install in UML (chrooted env was OK).

So today I got the default kernel config from my Ubuntu 9.10, made some nice changes (see below), had a nice chat with GDM (does not like me so far) and...

This is Gnome session from Karmic 9.10 running in UML connected to separate X server running at host computer. Unfortunately, Xnest does not work in such conditions generously exiting on

X Error of failed request:  BadDrawable (invalid Pixmap or Window parameter)
Major opcode of failed request:  70 (X_PolyFillRectangle)
Resource id in failed request:  0x0
Serial number of failed request:  51056
Current serial number in output stream:  51056

The nice changes included: Virtual block device was not compiled in by default, right, no support for virtual hard drive - CONFIG_BLK_DEV_UBD :). Additionally, MAKE SURE that you have CONFIG_HIGHMEM disabled - will not compile otherwise. CONFIG_BLK_DEV_UBD_SYNC MUST BE enabled, otherwise you will get the same filesystem corruption I tried to battle for several hours.

You might also need a set of patches for various compile-time errors. I have no idea why they were not included in the tree, but... The actual set of the links to patches will be provided here once I get to recompile the vanilla kernel again with a customized config to exclude the hardware that cannot be physically present in UML instance.

So far I am happy.