FreeBSD boot manager customization for single-disk multiboot (4 x DOS)

Polytropon freebsd at
Tue Oct 9 22:12:31 UTC 2018

On Tue, 9 Oct 2018 21:30:41 +0530, Manish Jain wrote:
> On 10/09/18 12:14, Wojciech Puchar wrote:
> >>
> >> I suggest a better way than to use FreeBSD/Linux boot manager.
> >>
> >> Create 1 primary partition + an EBR with 4 logical drives (with the 
> >> primary partition at the beginning of the disk).
> >>
> >> Install 4 x DOS/Win into the logical drives (all using the first 
> >> primary partition as C:)
> >>
> >> Finally and if needed, alter the boot.ini in C: as you wish.
> >>
> >> Does that solve your problem, or compound it ?
> > 
> > what is boot.ini? i don't remember something like this in DOS.
> I would have thought C:boot.ini was the standard bootloader 
> configuration file in DOS/Windows - it is, of course, standard in Windows.

In DOS, there is no such mechanism. It always needed some
external boot manager (or at least a BIOS where you could
choose a boot device, but that required individual disks
to boot from).

I'm not sure this facility is present in the older versions
of "Windows" (pre-2000) which are going to be installed on
that particular systems. I'm also unsure if it can handle
DOS correctly (even though it usually can handle Linux).

By the way, depending on the smallest disk I can find, it
_might_ be possible that I can install Linux too, and that
could be a chance to try Grub. This will make it possible
to use that particular laptop for adjacent amateur radio
purposes. I'm not sure if DOS will boot from a logical
volume inside an extended partition, so maybe I'm going
to have to rethink about the layout, maybe something like
this is possible:

	prim. part. 1 = DOS 5.0
	prim. part. 2 = DOS 6.22
	prim. part. 3 = data exchange (FAT)
	ext. part = {
		log. vol. 1 = Windows '95
		log. vol. 1 = Windows '98
		log. vol. 1 = Linux swap
		log. vol. 1 = Linux ext2

With Grub, setting "boot paths" to the five systems installed
should be no problem. At least this was possible in much older
versions of Grub (I used that to boot DOS or OS/2 or Linux in
the past) - no idea if it still works...

> Since Windows 98 would getting installed last, its boot manager should 
> configure the boot environment correctly.

That's highly questionable, given the "urge" of destroying
existing MBR data that "Windows" usually seems to feel. The
common instructions of building multi-boot environments
therefore often include the advice to install "Windows"
first, and end with the OS that will install the boot manager,
or if that's not possible, re-install (!) the boot manager
after "Windows" has been installed.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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