empty /proc

[Haines Brown <haines@histomat.net>]

I did a cross install of Jessie from Wheezy. When the system is booted,
there is a symlink from /etc/mtab to /proc/mounts, but /proc is empty or
not mounted. This has some consequences.

I mount proc:

  # mount /proc

Now mount displays what is mounted, and proc is mounted.

mount: /proc: mount failed: Unknown error -1

In my host Wheezy system, # mount shows proc as mounted, although there
is no line to do it in fstab. But in the target Jessie disk, /proc is
empty and not mounted unless this line is present in its fstab:

   none /proc proc defaults 0 0

My question is: a) how can my Wheezy system mount proc when there is no
command fstab to do it? b) why does my Jessie system not mount proc and
thus populate /proc unless the line is present?

Haines Brown