document updated 15 years ago, on Sep 8, 2009

My multi-boot setup is on a portable USB drive. The main partition is FAT32.

Each thing that's booted needs to reside in its own subdirectory:

\boot\MSDOS7.1\
\boot\Knoppix\
\boot\PuppyLinux\
\boot\Hiren\
\boot\VistaPE\

However, sometimes it takes work to relocate each OS into a specific subdirectory — most are used to having the root directory all to themselves. An alternate method to this document's approach is to instead allocate one partition per OS.

Several commands work only on one GRUB variant. (see documentation for more)

Key
GRUB Legacy
GRUB4DOS
Super Grub Disk

Linux-based

Debian Live

It includes an example menu.lst, see here.

See live-initramfs(7) for boot parameters. Notably:

live-media=DEVICE
live-media-path=PATH

Clonezilla Live

See "Debian Live".

For default parameters, see the syslinux/syslinux.cfg file inside the Clonzilla Live distro.

Note: Clonezilla can't save images to the same partition that it booted from, so you may have to create a separate partition for Clonezilla to boot from.

NOTE:: The above may be fixable with the command `sudo mount -o remount,rw /cdrom` (I haven't tested it yet, but it works on Knoppix)

Knoppix v6.x

title Knoppix
    kernel          /boot/Knoppix/boot/isolinux/linux knoppix_dir=/boot/Knoppix/knoppix/ ramdisk_size=100000 lang=en vt.default_utf8=0 apm=power-off vga=791 initrd=minirt.gz nomce elevator=anticipatory quiet loglevel=0 pci=routeirq
    initrd          /boot/Knoppix/boot/isolinux/minirt.gz

Knoppix v5.x

title Knoppix
    kernel          /boot/Knoppix/boot/isolinux/linux knoppix_dir=/boot/Knoppix/knoppix/ ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 initrd=minirt.gz nomce quiet BOOT_IMAGE=knoppix
    initrd          /boot/Knoppix/boot/isolinux/minirt.gz

See boot parameters here. Notably:

bootfrom=/dev/hda1
bootfrom=/dev/hda1/knoppix.iso
knoppix_dir=boot/knoppix (no slashes before or after; you may have to adjust the capitalization)
knoppix_name=cloopfile

For some reason, I can't get knoppix_dir to work at all, so I always end up having to put the very large cloop file at \Knoppix\Knoppix.

To be able to write back to the USB drive, run `mount -o remount,rw /cdrom` after booting. Put this command in knoppix.sh in order to have this automatically work every bootup.

Damn Small Linux

It's Knoppix-based. Useful cheat codes are:

knoppix_dir=boot/knoppix

Puppy Linux

title Puppy Linux
    kernel /boot/Puppy/vmlinuz acpi=off psubdir=boot/puppy
    initrd /boot/Puppy/initrd.gz

Boot parameters are here, notably:

pkeys=us
psubdir=puppy216
- no slashes before or after
- it can't be more than one directory deep. (i.e. psubdir=puppy will work, but psubdir=boot/puppy won't work) (discussion).
  However, you can modify the initrd to make multiple levels work:
  - Gunzip the initrd.gz file
  - Open it in a hex editor
  - Search for "maxdepth", and increase the numbers after them by one (e.g. "-maxdepth 2" to "-maxdepth 3")
  - Gzip back to initrd.gz.

tomsrtbt v2.0.103

title tomsrtbt
    map --mem /tomsrtbt-2.0.103.ElTorito.288.img (fd0)
    map --hook
    chainloader (fd0)+1
    rootnoverify (fd0)

You can download the tomsrtbt-2.0.103.ElTorito.288.img.bz2 from various places, but you need to unzip it.

Unfortunately, the boot process goes through MEMDISK ⇒ LILO, so you can't set any boot parameters from the outside.

DOS-based

MS-DOS

Download files from http://ms-dos7.hit.bg/.

Unfortunately, MS-DOS must have the following several files in the root directory: io.sys, msdos.sys, config.sys, and autoexec.bat. Some things can move, however:

io.sys — if you chainloader it, it can be loaded from anywhere
command.com — specify its location with shell= in config.sys.
msdos.sys — in v7+, if you want all-default values, then you can actually just delete this file, it's optional (however, this turns on boot logging by default, which adds another file to the root directory, so it's probably better to just leave it there)
some files can only be moved by putting them on a virtual floppy:
- autoexec.bat, config.sys

title MS-DOS
    chainloader /boot/msdos7.10/io.sys
    boot

Hiren's Boot CD

Copy the entire BootCD\ directory somewhere under your main MS-DOS partition. (for me, it goes in \boot\Hiren\BootCD\)
Modify loadcd.bat, and right after the first call to findcd, add this:
```
set CDROM=C:\boot\Hiren\
```
Remove jo.sys from the floppy image.
Package those files back into a standalone boot floppy file.

Use this in menu.lst:

title Hiren's Boot CD   v9.5

    map --mem /boot/Hiren/h95_fd0.img (fd0)
    map --hook
    chainloader (fd0)+1
    rootnoverify (fd0)
    map --floppies=1
    
    boot

This way, no CD-ROM drivers are needed at all. The boot partition already appears under Hiren's as C:, so we just leverage that.

(This is a small modification of the official Hiren's-on-USB. We leave the files packaged inside a floppy image, so that we can boot from different config.sys's elsewhere, but leave the config.sys-based menu intact for Hiren's.)

Windows-based

Windows PE 1.0

See also: /apps/WinPE/booting.html.

The standard bootloader requires files to be in /i386/ (if using an ISO9660 filesystem) or /minint/ (if using a FAT/NTFS filesystem). To move it elsewhere:
- hex-edit setupldr.bin and change all instances of "i386" to the directory you want (but it has to be a 4-6 letter directory :( )
- edit txtsetup.sif and change i386 to the desired subdirectory
When booting from a USB device, you have to copy setupldr.bin and ramdisk.sys from Windows 2003, and boot from a RAM disk. (otherwise the USB bus is reset during bootup, causing the drive to disconnect)

Windows PE 2.0 (e.g. VistaPE)

the files you need (these are from a VistaPE build) are::

\bootmgr
\vistape.cfg
\vistape.wim
\boot\bcd
\boot\bcd.log
\boot\boot.sdi
\boot\etfsboot.com

files that can't move (unless you put them on a virtual floppy):
- \boot\bcd
- \boot\bcd.log
files that can be moved:
- \boot\etfsboot.com — only needed if you're booting a CD/DVD, specify via mkisofs -b
- \bootmgr — if you chainloader this from GRUB4DOS, it doesn't matter where you put it
- \vistape.wim — the largest file, move it to \boot\vistape\vistape.wim, and bcdedit the device and osdevice entries
- \boot\boot.sdi — bcdedit the ramdisksdipath entry
boot with this (after moving /BOOTLOADER to this subdirectory):
```
title VistaPE
    chainloader /boot/VistaPE/BOOTLOADER
```

Recovery Console

title Windows Recovery Console
    chainloader /cmdcons/setupldr.bin
    #####################################################################
    # write string "cmdcons" to memory 0000:7C03 in 2 steps:
    #####################################################################
    # step 1. Write 4 chars "cmdc" at 0000:7C03
    write 0x7C03 0x63646D63
    # step 2. Write 3 chars "ons" and an ending null at 0000:7C07
    write 0x7C07 0x00736E6F

Other

memtest86+

download the "pre-compiled package for floppy"

use this to boot the floppy image:

title memtest86+
    map --mem /boot/floppies/memtest.img (fd0)
    map --hook
    chainloader (fd0)+1
    rootnoverify (fd0)
    boot

Advice

If your boot files are stored on FAT, then booting Linux sometimes causes uppercase/lowercase issues. FAT considers directory names to be case-insensitive, but most initrd scripts I've seen treat FAT filenames the same as ext2 filenames — they expect the exact desired case to be used.
- Mount the FAT on a Linux distro, and set up all your files there. This way you carefully control the case from the beginning.
- Under DOS/Windows, try different combinations of uppercase/lowercase for the paths leading up to the main files.
- Under DOS/Windows, try different combinations of uppercase/lowercase for the files themselves (it's helpful to know exactly which filename the distro itself triggers off of)
- If still stuck, see the "debugging initrd" link below.