This is kept up-to-date in mainline, so get the kernel of your choice
from kernel.org and
build UML from it.
This tarball contains
uml_net, uml_mconsole, uml_switch, tunctl, and a number of other
useful utilities. Go here for
details on building and installing them.
These are host patches which UML uses to run noticably faster. SKAS3
has been around for years, is widely used, and is considered stable.
The latest patch, for 2.6.23, is here. All versions of UML will
detect the SKAS3 patch on the host and use it if it is present.
SKAS4 exists because the SKAS3 patch can't be merged to mainline
because the interfaces it implements are wrong. SKAS4 implements the
same functionality under a much nicer interface.
The current SKAS4 patch, against 2.6.24, is here.
This is experimental. In order to use it, you should build both the
host and UML from the same tree. Full details are also available at
the link above.