Comment 2 for bug 296089

For anyone who is trying to do this (for example to get a reproducible clean environment for testing purposes) and missing the essential steps, they are:

* set your DHCP server up to hand off to a TFTP server. For example, add the following lines to your subnet definition in /etc/dhcp3/dhcpd.conf:

        next-server 10.0.156.34;
        filename "pxelinux.0";

* get a copy of pxelinux.0 from the pxelinux package and put it in the tftproot of your TFTP server.

* copy the casper directory off the CD and put it into your tftproot as well.

* get an NFS server on your network to loopback-mount the Desktop ISO (e.g. ubuntu-8.04.2-desktop-i386.iso) and export the mount directory through NFS. Let's say your NFS server is 1.2.3.4 and the ISO is mounted at /var/nfs/ubuntu/live. Edit /etc/exports on the server and export the mount directory to the world by adding the following line:

/var/nfs/ubuntu/live *(ro,all_squash,no_subtree_check)

* put the following section into your tftproot/pxelinux.cfg/default file:

DEFAULT live-804
LABEL live-804
  kernel casper/vmlinuz
  append file=/cdrom/preseed/ubuntu.seed boot=casper initrd=ubuntu/ubuntu-8-04/casper/initrd.gz netboot=nfs nfsroot=1.2.3.4:/var/nfs/ubuntu/live quiet splash --

* test that the PXE client boots into the live CD environment

* if it doesn't, remove the "quiet splash" from the end of the "append" line and boot it again, to see where it gets stuck.

I hope this helps someone, and that NFS-booting a live environment will be properly documented one day.