[BusyBox] pb installing bbox from initrd ?

[Jacques Nilo]

I am trying to install busybox (0.6.2) from a compressed initrd fs.
My kernel cmdline looks like:
linux initrd=initrd.gz root=/dev/ram0 init=/linuxrc ...

The first lines of my linuxrc look like:

#!/bin/busybox ash
exec /bin/busybox mount -t proc proc /proc
exec /bin/busybox --install -s

With such a setting I get a kernel panic:
Freeing initrd memory: 428k freed
VFS: Mounted root (minix filesystem).
Kernel panic: Attempted to kill init!

If I do not mount the /proc fs then I get an error message 
/proc/self/exe: No such file or directory (which is OK since the --install 
option requires the /proc fs)

Could it be related to the fact that I am trying to use busybox ash to do 
that ?
What could be the problem ?
Thks
Jacques