[issue762] missing 's0' in device use

[Chris Turner]

Nicolas Thery wrote:
> 
> Anybody knows what /etc/fstab is used for in the vkernel env?
> 
Any other mounted filesystems as usual..
see /etc/rc.d/mountcritlocal, etc.

The vkernel boots on the first partition in the vkd by default,
see init_vkd in sys/platform/vkernel/platform/init.c:705
(sets to vkd0s0a for VKD_DISK and cd9660:vcd0a for VKD_CD)

Probably good to have fstab and the docs match something that works
(as discussed elsewhere)
in case you want the shorthand to 'mount -o rw /'
after an unclean shutdown, mount -a from vcd booted chroot,
etc..