Hallo!
Some time ago i did experiment with dual-booting (actually
multi-booting) from one harddisk several OpenBSD instances, for the sake
of fun. I settled to using dualboot OpenBSD to make upgrades more
suitable for me (just unpacking new distribution's file sets under /mnt
mounted empty partition and rebooting).
But as i see it there is to ways of having multiple root i.e. a
partitions on one physical harddisk
1. Use only one fdisk partition and in it one OpenBSD root is normal a
partition and another is in the same disklabel, say g. And so for
example in this disklabel a, d, e, f partitions belong to one instance
and g is another (consisting of one filesystem). Two instances share
only swap partition.
To select between them you need to say at boot> prompt
boot> boot hd0a:/bsd
or
boot> boot hd0g:/bsd
2. Use severaly fdisk partitions, each has its own disklabel and this
disklabel is dedicated to one OpenBSD instance. OpenBSD bootloader is on
To select between instances you need to use grub bootloader from binary
packages
# pkg_add grub
It goes like this that grub's first stage is in the harddisk's MBR and
openbsd bootloader's first stage is installed into each fdisk partition,
i.e. you use chainloading.
See also
/usr/local/share/doc/grub/README.OpenBSD
/usr/local/share/examples/grub/menu.lst
Essential is to understand that OpenBSD uses first fdisk's OpenBSD A6
disklabel it sees. Thats why grub fiddles with them.
Take care, it is very good oppurtunity to make your system unbootable or
loose even more than just that!
Imre
Leo Baltus wrote:
