This is, what rootstrap does, however simplified so one can do it by hand. Why is this useful? It is very simple to get a running user-mode-linux by just copying the linux.uml and slirp-fullbolt binaries to some target system. Of course, you then don't have rootstrap. So this is, how that works:
$ dd if=/dev/zero of=rootimage bs=1 seek=1G count=0
$ /sbin/mke2fs -F rootimage
$ dd if=/dev/zero of=swapimage bs=1M count=128
$ /sbin/mkswap swapimage
$ /path/to/linux.uml \
root=/dev/root rootflags=/ rootfstype=hostfs \
ubda=rootimage \
ubdb=swapimage \
eth0=slirp,,/path/to/slirp-fullbolt \
init=/bin/bash
Now we continue within the uml boot. We are root now (within uml):
# mount -t tmpfs tmpfs /etc # mount -t tmpfs tmpfs /dev # mount -t tmpfs tmpfs /tmp # mount -t proc proc /proc # mkdir /tmp/host # mount -t hostfs hostfs /tmp/host # cp /tmp/host/etc/passed /etc # cp /tmp/host/etc/group /etc # cd /dev # /tmp/host/dev/MAKEDEV ubd # swapon /dev/ubdb # mkdir /tmp/target # mount /dev/ubda /tmp/target # echo 'nameserver 10.0.2.3' >/etc/resolv.conf # ifconfig eth0 10.0.2.15 netmask 255.255.0.0 # route add default gw 10.0.2.2 # cd /tmp # export PATH # debootstrap <suite> /tmp/target # umount /tmp/target # /sbin/halt -f
We now have a basic filesystem image in rootimage. We can now contine as in Simple User Mode Linux Setup On Debian (after the rootstrap step) and boot into this new image to configure it.