freebsd stable - Jan 2004 - #2 - Swapped disks and now stuck in the mountroot> prompt

Date: 12 jan 2004

I've installed FreeBSD 4.9 on a ide0:0 (primary IDE, master hd) then
ported the hard disk on a second PC and installed as ide1:0 (secondary
IDE, master hd) without update the "/etc/fstab" file.

When booting the kernel start probing devices, I see the disk as "ad2"
then the kernel halts when trying to mount the root file system with the
following message:

       mount root from ufs:/dev/ad0s1a
       root mount failed: 6

At the prompt I've tried with "ufs:/dev/ad2s1a", now the right
device, but
it does not work.

The solution is to instruct the kernel with the right device: but ad2s1a
seems to be wrong...

After several attempts I discover that the kernel must be started with the
option "-a": with this flag the device "ufs:/dev/ad2s1a" is
accepted by
"mountroot> " and the boot proceed. Than I can change the fstab
accordingly to make the change permanent.

My question are:
 1) I've made any mistake ?
 2) Without the boot "-a" flag, why the kernel ask me a device and
even it
is the correct one vfs_conf.c:vfs_mountroot_ask() give me the error code
6?


Thanks
Roberto