[uClibc] Readonly root filesystem a la Pebble

Rob Landley rob at landley.net
Tue May 10 02:28:01 UTC 2005


On Monday 09 May 2005 02:01 pm, Doyle, Patrick wrote:
> I was wondering if anybody has done any work to create a read only root
> filesystem, such as that used in pebble, that can be tweaked occasionally.
> Basically, I would expect that it would be an ext2 filesystem with symbolic
> links to volatile information pointing to files in /var.
>
> Any thoughts?  Any pointers?
>
> --wpd

My pet project (www.landley.net/code/firmware) makes a read-only root 
filesystem, but it's just a testbed for weird ideas (such as replacing all 
the gnu command line utilities with busybox and trying to actually compile 
software with the result).

If you're going with a readonly rootfs, I can highly recommend squashfs.  
Keep /var writeable (it can be a ramfs if you keep your logs trimmed), and 
some things in /etc want to be writeable too.  (It's a bit of work sorting 
out /etc, I just made it a symlink into a subdirectory in /var, because I'm 
lazy. :)

Oh, and if /dev is readonly logins can't chown the tty.  Use udev and a ramfs 
for that too...

Rob



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