[BusyBox] followup on mount oddity from my previous email

[Robert P. J. Day]

On Thu, 11 Dec 2003, Rob Landley wrote:

> On Thursday 11 December 2003 16:25, Robert P. J. Day wrote:
> > On Thu, 11 Dec 2003, Rob Landley wrote:
> > > On Thursday 11 December 2003 15:31, Robert P. J. Day wrote:
> > > > On Thu, 11 Dec 2003, Erik Andersen wrote:
> > > > > On Thu Dec 11, 2003 at 07:59:02AM -0500, Robert P. J. Day wrote:
> > > > > > mount: Mounting /dev/root on / failed: No such file or directory
> > > > > > rm: unable to remove `/etc/mtab': Read-only file system
> > > > > > ln: /etc/mtab: File exists
> > > > > > Mounting local file systems...
> 
> You know, it looks like the _MOUNT_ is what's failing.  The fact the
> filesystem is read-only is a side effect of the mount failing.  So all
> the mtab support stuff is a red herring: the system is screwed up before
> it gets to that point.
> 
> Could you walk us through how your system is supposed to come up?  
> (What's the section of init script that does the mount that's failing
> above?  Is there a /dev/root entry in the filesystem that's there at the
> time?)

i finally came to this conclusion as well.  as an abridged form of what i
had posted earlier, here's the offending snippet of code in
/etc/rcS.d/S10checkroot.sh:

  mount -n -t proc /proc /proc
  echo "Remounting the root filesystem read-write."
  mount -n -o remount,rw /dev/root /        <-- that's failing
  rm -f /etc/mtab~ /etc/mtab /etc/nologin
  ln -s /proc/mounts /etc/mtab

once my eval board boots the kernel, i pass it the essential parms to
NFS-mount the root filesystem from the server.  it does this by mounting
read-only, and that root filesystem contains /linuxrc -> bin/busybox.

eventually, as you can see above, the root filesystem should be re-mounted
read-write, but that "mount" command fails, saying (from memory here):

  /dev/root on /: No such file or directory.

there is no device file /dev/root, since i'm using devfs, which has worked
fine until now.  so, a much simpler question would be: what options do i
need to have in busybox to support the remounting of the root filesystem
read-write?  clearly, i'm forgetting an option that's causing that single
command to fail, and all other problems cascade off of that one.

rday