Re: [gentoo-dev] Further observations on moving root

[Fuper <futurist@directvinternet.com>]

If you ever might add a new disk drive and want to move the Gentoo
root partition onto the new (maybe faster) drive then my struggles
in doing that may be relevant to you.  Copying the partition didn't
just work --- I found that the /dev directory initialization was not
obvious.

I did conclude to my own satisfaction that the /sbin/rc script (v. 1.16) 
is in error at line 312 and should read as follows:
   309  #we want devfsd running after a change of runlevel (if we return
   310  #from runlevel 'single')
   311  if [ -z "$(ps -A | grep devfsd)" ] && \
   312     [ -n "$(cat /proc/mounts | grep -e '/dev devfs')" ]
   313  then
   314          /sbin/devfsd /dev &>/dev/null
   315  fi
The distributed script had "cat mounts" and failed when devfsd
was not already running.

After reading the devfs FAQ and Robbins paper on devfs at 
IBM:developerWorks I concluded that a cleanly built root
partition should have an empty /dev directory.  It is entirely
populated by devfs when that is "mounted" and accessed.

BUT Gentoo linux, installed from build rc6 r14, crashes when
booted from the same /boot partition but using a new root ("/")
and an empty /dev (it had more interesting problems when 
I attempted to create a fully populated dev/ by copying the
in-use /dev from the old root partition onto the new partition
s.a.
   star -c /dev | star -x -C /mnt/partition  # Don't do this

I had to add the devfs mount option to the kernel so that
the grub commands that had been
  root (hd0,0)
  kernel /boot/bzImage root=/dev/hda2 hdc=ide-scsi
became now
  root (hd0,0)
  kernel /boot/bzImage root=/dev/sdb1 hdc=ide-scsi devfs=mount

It is a mystery to me why it now becomes necessary to add
the devfs=mount option to the grub kernel command, booting
the same kernel using the same devfs.conf file and same 
root partition (but copied onto a new disk).  If this is obvious
to everyone else, then so be it; but maybe it is worth 
documenting that under some conditions it becomes
necessary to add the kernel option.

I hope that this is helpful.