Bootloader two-drive dual-boot configuration question

Paredes Sánchez Martín A. MPAREDES at
Wed May 14 12:51:15 PDT 2003

If I understand, you want to boot from disk 1 (this has to be made in BIOS) and be asked what to boot (Windows or FreeBSD).

Is the same than booting fron disk 0 (no special configuration needed) and be asked what to boot (Windows or FreeBSD)

BootEasy is the program in FreeBSD that give the multiboot facility or bootmanager (the F1 ??? and F5 ...), this program, when installed,  is stored in the MBR (Master Boot Record) of disk 0, so you can say tha none OS is booted when you see the menu "F1 ??? and F5 ...". Because of this, the size of this program is restricted to 512 bytes.

The BootEasy program check how many "primary partitions" are in the disk (only can be a maximum of 4 primary partitions per disk), since you have only 1 partition on disk 0, F1 is printed in your monitor. Then BootEasy check how many disk are in the computer and print F5 for disk 1, F6 for disk 2 (you don't have this) and so.

I think you use more FreeBSD, so you want to boot FreeBSD with 1 key stroke (not like now, pressing F5 then F1, 2 key strokes), to do this, you need to modify the BootEasy program.

If you have the CD 1 of installation, look in \TOOLS\SRCS\BTEASY, there is a README file and the sources of this program, the BOOT.ASM is the program that goes to the MBR, you do this with the BOOTINST program witch is in \TOOLS. 


	-----Original Message-----
	From:	David Gerard [SMTP:fun at]
	Sent:	Sunday, May 11, 2003 2:34 PM
	To:	freebsd-questions at
	Cc:	lilith at
	Subject:	Bootloader two-drive dual-boot configuration question

	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

	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 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?

	- d.

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