using initrd for dhcp+rootnfs

Since people seem to at least want the bootp to go away in the kernel, I
thought I'd try to build myself an initrd which has a usermode dhcp and
try go get it to do root-nfs.

According to linux/Documentation/initrd.txt:

<SNIP>
It is also possible to change the root device from within the initrd
environment. In order to do so, /proc has to be mounted. Then, the
following files are available:

  /proc/sys/kernel/real-root-dev
  /proc/sys/kernel/nfs-root-name
  /proc/sys/kernel/nfs-root-addrs

real-root-dev can be changed by writing the number of the new root FS
device to it, e.g.

  # echo 0x301 >/proc/sys/kernel/real-root-dev

for /dev/hda1. When using an NFS-mounted root, nfs-root-name and
nfs-root-addrs have to be set accordingly and then real-root-dev has to
be set to 0xff, e.g.

  # echo /var/nfsroot >/proc/sys/kernel/nfs-root-name
  # echo 193.8.232.2:193.8.232.7::255.255.255.0:idefix \
    >/proc/sys/kernel/nfs-root-addrs
  # echo 255 >/proc/sys/kernel/real-root-dev
</SNIP>

This is fine by me.  There's just one problem - the
/proc/sys/kernel/nfs-root* files were removed in kernel v2.1.75!!  Is the
documentation out of date and there's a new-and-improved way to do
this?  How do I set these values?

	-kf