Mystery of chroot

[Timothy Murphy]

This is a purely theoretical question.

Yesterday I re-installed Windows XP on /dev/sda1 on my laptop
(I'd used dd to try to copy Windows from a smaller partition,
and while this booted it had a number of bizarre error).

Anyway, this removed grub from the MBR,
so I used Knoppix to re-install grub,
which I did without problem by running
        grub-install --root-directory=/mnt/sda5 /dev/sda

I was surprised how long this took - over 10 minutes
on a ThinkPad T43 (800MHz with 512MB RAM).
Admittedly the new disk is quite large, 120GB,
but what exactly is grub-install doing?

But that isn't my question.
My first attempt to re-install grub
was to mount /dev/sda5 as /mnt/sda5
and then run "chroot /mnt/sda5".
What puzzled me is that after this /dev/sda was not found.
Why is this?
Does one have to run something like udevd after chroot now?

-- 
Timothy Murphy  
e-mail (<80k only): tim /at/ birdsnest.maths.tcd.ie
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mat00hematics, Trinity College, Dublin 2, Ireland