tar --bzip -xvf linux-2.6.1.tar.bz2
	cd linux-2.6.1
	bunzip2 -c ../uml-patch-2.6.1-1.bz2 | patch -p1

	cp config.pjd-2.6.1uml .config
	make ARCH=um oldconfig
	make ARCH=um linux

	./linux ubd0=root_fs_slack8.1 ubd1=slackware-8.1-install.iso

It should make it all the way through boot and give you a login prompt, as well as popping up three other xterms for the other virtual consoles.  Note that to stop the program you have to log in (root, no password) and run the 'halt' command.

It's a good idea to save a copy of the original root_fs_slack8.1.bz2 file, so that if you screw up your root filesystem you can just delete it and start over. Also, for obvious reasons UML locks a file that it's using as a virtual disk, so you can't have two UMLs running against the same disk image at once.  (well, not with the UBD driver.  There's a copy-on-write driver that lets you do this...)

Setting up the virtual system

If (like me) you don't know anything about Slackware, you'll want to know that installed packages are listed in /var/log/packages (each file has the name of a package, and contains a list of its files) and you add and remove packages with the installpkg and removepkg commands.  Mount the ISO image ('mount /dev/ubd/0 /mnt/cd') and you'll have access to all of them.

Also you'll probably want access to the host filesystem to transfer files back and forth, using the 'hostfs' filesystem.  To add /mnt/host to your fstab:

	mkdir /mnt/host
	echo none hostfs defaults 0 0 >> /etc/fstab

Setting up networking

The only networking method that doesn't require root access is Slirp, and I haven't been able to get that to work. (well, I did get it to work on kernel 2.4.22, but that doesn't help here)  More info when I have something that works.