FreeBSD two-drive dual-boot configuration question.

[reddragdiva]

(This entry is far too geeky for most of my readers to want to even think about. But there are enough of you who aren't, and I couldn't deny you the pleasure. I just posted the following to freebsd-questions ...)

I am setting up an IBM 300PL (Model 6862-N2U) which is intended to dual-boot Windows and FreeBSD 4.8-RELEASE. As the BIOS will happily boot from any IDE hard disk, we wanted to set it up with the present Windows installation on drive 0 (the master - which FreeBSD sees as ad0) and a fresh FreeBSD installation on drive 1 (the slave - which FreeBSD sees as ad1).

We installed FreeBSD and it's working fine on drive 1. However, going to the BIOS to configure which OS to boot into is annoying. So it would be nice to do it in the boot loader. However, I can't see what to give boot0cfg to do this (assuming that's the right program to use).

(The options boot0 [the FreeBSD MBR boot loader] gives are F1 - FreeBSD; F5 - Drive 1 ... note that FreeBSD is on drive 1.)

I tried swapping the disks - so the FreeBSD disk was drive 0 and the Windows disk was drive 1. However, FreeBSD would not boot - the disk was expecting to find itself as ad1s1a, and mountboot wouldn't accept ufs:/dev/ad0s1a as I would have expected. So I put the disks back the way they were and we're presently selecting which disk to use via the BIOS.

Is there a way to do what we want with boot0? That is: boot from drive 1, then bring up a boot menu allowing us to select between booting off drive 0 or drive 1?

Update: There is an answer. (But don't let that stop you from posting yours!)

Comments

[azekeil.livejournal.com]

Hmmm, usually for that you want to install the boot loader in the MBR of HDD0. If you've installed doing the BIOS swappy thing it might make life more difficult now. See if there are some options for installing the MBR in HDD0.

Which version of Windows are you using? I ask because if it goes hideously wrong, 2000/XP (and possibly NT) have a command-line rescue utility from which you can rewrite the MBR again.

[reddragdiva]

It's Win98SE. fdisk /mbr if necessary. But it should be right (fingers crossed).

[azekeil.livejournal.com]

Doh, of course you can.

/me forgets my DOS heritage in a haze of Linux-fueled geekiness.

[mjg59.livejournal.com]

It's been some time since I touched FreeBSD - but something like

boot0cfg -B -d 0x80 wd0

ought to install it in the first disk's MBR rather than the second, which may improve things.

[hythloday.livejournal.com]

You can do this with GRUB, but I doubt you want to replace your bootloader, so this isn't really worth posting - sorry :-)

[reddragdiva]

I considered it (and there's enough how-tos out there), but the approved method (put the FreeBSD boot0 on drive 0) looks like the right answer and is also easily recoverable in case of trouble ...