[BusyBox] busybox loads, then i get "NFS root" mount errors

[Robert P. J. Day]

  this is probably not directly related to busybox operation, but i've been
fighting with this all morning and i'm not sure who else to ask.  (i'm a
beginner with busybox so i hope i'm using the correct terminology.)

  i'm using bb-1.0.0-pre3, and i started with a combination kernel/ramdisk
that downloaded and ran just fine on a PowerPC evaluation board.  from
that, i took the ramdisk image for the root file system, gunzipped it, and
mounted it (using "-o loop") to take a look.  that image had a bb-0.60.0
busybox and numerous symlinks, all under /bin, /sbin, /usr/bin and 
/usr/sbin, pretty much what i expected to see.

  ok, i thought, i'd like to upgrade, so i built a new busybox (statically
linked because of a libcrypt lib issue), removed all of the above directories
and loaded the new busybox build in place.  all of the binaries went into
the proper locations, the symlinks looked good, and so on.  i didn't touch
anything else in the root filesystem -- all startup scripts were left as is.

  i bundled that ramdisk image back up again, created a new download 
image, booted and what i got was (an excerpt where you can see the
kernel after it's loaded and starting to gunzip and mount the ramdisk
image):

------------------------------------------------------------------------

NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
RAMDISK: Compressed image found at block 0
Freeing initrd memory: 2385k freed
VFS: Mounted root (ext2 filesystem).
Mounted devfs on /dev.Using fallback suid method
BusyBox v1.00-pre3 (2003.11.11-10:15+0000) multi-call binary

Usage: busybox [function] [arguments]...
   or: [function] [arguments]...

        BusyBox is a multi-call binary that combines many common Unix
        utilities into a single executable.  Most people will create a
        link to busybox for each function they wish to use, and BusyBox
        will act like whatever it was invoked as.

Currently defined functions:
        [, addgroup, adduser, ar, ash, basename, bunzip2, busybox, bzcat,
        cat, chgrp, chmod, chown, chroot, clear, cp, cpio, crond, crontab,
        cut, date, dd, delgroup, deluser, df, dirname, dmesg, dpkg, dpkg-deb,
        du, echo, env, false, fgrep, find, free, ftpget, grep, gunzip,
        gzip, halt, head, hostname, hwclock, id, ifconfig, init, insmod,
        kill, killall, klogd, ln, logger, login, logname, ls, lsmod, md5sum,
        mesg, mkdir, mkfifo, mknod, modprobe, more, mount, mv, netstat,
        nslookup, pidof, ping, poweroff, ps, pwd, reboot, reset, rm, rmdir,
        rmmod, route, rpm, rpm2cpio, run-parts, sed, sh, sleep, sort,
        start-stop-daemon, sync, syslogd, tail, tar, telnetd, test, tftp,
        touch, true, tty, umount, uname, uncompress, uniq, unzip, uptime,
        wc, which, whoami, xargs, yes, zcat

Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "" or 02:00
Please append a correct "root=" boot option
Kernel panic: VFS: Unable to mount root fs on 02:00
Rebooting in 180 seconds..  

--------------------------------------------------------

  ok, i'm baffled.  from what i read, the root filesystem has already been
mounted, so what's with the NFS-related errors.  as i said, i'm not sure
how this relates to busybox since it seems to at least get invoked.  
(at boot time, there is a symlink /linuxrc -> bin/busybox that was used
in the older ramdisk image, so i just left it there.)

  can anyone give me a hint as to what i should be looking at?  as much
as possible, i tried to leave everything untouched except for replacing 
the older busybox with the newer version (and building statically, as i
mentioned).

  thoughts?

rday