On Thu, Aug 25, 2005 at 10:01:43PM -0700, Jerry VanBrimmer wrote:
> Okay, I got all the way up to where sysinst asked if I wanted to make
> the NetBSD partition active. I answered 'Yes', but it never set it
> active. And, in the partition options pop-up menu, I cannot even select
> the Set Active option. I don't *think* I did anything wrong, so all I
> can think of is that sysinst won't allow a partition on an extended
> partition to be set active. Any ideas?

Only the four main mbr partitions (and excluding the base of the extended
partition chain) can be set 'active'.  This is enforced because some system
BIOS won't boot the system at all unless one of the main partitions is
marked 'active' (and even looks as though it has code in it).

Remember that the 'active' flag is used by simple mbr code to determine
which pbr to load (the pbr code has to re-read the mbr table but will
normally look at the partition type - which is one thing that makes it
difficult to have 2 copies of a similar OS on the same disk).

If you need to boot from one of the extended partitions you typically
have multiple OS installed, and some form of boot-select program in use.
Whether a partition is marked 'active' is then usually totally irrelevant.

It is also worth remembering that both lilo and grub are much, much larger
than space actually reserver for the first level disk bootstrap, and
probably also much larger that allocated by most filesystems for boot code.
(The mbr code has less that 446 bytes, UFS typically allows 8k.)
This means that they will be reading code out of (one of) the filesystems,
if you re-einstall (or newfs) that filesystem you disk is immediately
unbootable.

The netbsd bootselect code resides entirely within its allocated space,
so can (ok should) be able to boot (the pbr code) for any partition
on the disk, even if you reinstall the netbsd area.
(this is the main reason its UI is so terse)

	David

-- 
David Laight: david@l8s.co.uk