Say you want to be able to boot multiple different tools or operating systems from a single USB memory device (thumb drive, SD card, etc.), then you can create one using my recipie and extend my example configuration.
While I don't provide the ISOs here, the creation of the device, including installation of grub, with some examples for the grub.cfg are provided.
Since I routinely use this for various environments (including serial consoles), I keep the configuration of GRUB simple - all text based, no graphics, no bling.
The easiest option is a canned setup. However, since this destructively mangles whatever device you tell it to, I suggest you READ CAREFULLY and then perhaps try the script:
./bin/mkmb.sh
It should create and populate a reasonable structure, including copying over the template grub.cfg and any available ISOs you've already downloaded.
First step is to create a bootable device, in my case a system embedded sd card, but works equally well for a USB stick.
$ lsblk -d -io KNAME,TYPE,SIZE,MODEL
KNAME TYPE SIZE MODEL
....
sdb disk 972M Internal Dual SD
$ parted /dev/sdX
> mklabel msdos
> mkpart primary fat32 1 100%
> set 1 boot on
> quit
$ mkfs -t vfat /dev/sdX1 # or -t fat32
$ mkdir /tmp/multiboot
$ mount /dev/sdX1 /mnt/multiboot
$ grub-install --force --no-floppy --boot-directory=/mnt/multiboot /dev/sdX
Note that I tried FS type EXFAT, but that caused grief with some distros - error about "unknown file system type" on boot (from iso).
Then, setup the file system structure (arbitrary, but cleaner, IMO)
$ cd /mnt/multiboot
$ mkdir iso
$ wget -nc -o iso/DISTRO.iso http://..../<DISTRO>.iso
As an example for Ubuntu 16.04, you can fetch:
http://archive.ubuntu.com/ubuntu/dists/xenial/main/installer-amd64/current/images/netboot/mini.iso
Once you've got it started, just add new iso(s) to your iso subdir and edit grub.cfg. When you first get started, chances are there is NOTHING (or no file) for your /mnt/multiboot/grub/grub.cfg, but if there is, modify it to suit your distro needs, but here is an mini example to get you started (or see my current full one):
# Timeout for menu
set timeout=60
# Default boot entry
set default=0
# Menu Colours
set menu_color_normal=white/black
set menu_color_highlight=white/green
# 9.x/Stretch: http://ftp.nl.debian.org/debian/dists/stretch/main/installer-amd64/current/images/netboot/
menuentry "Debian 9.x/Stretch - AMD64 Mini/Netboot-Installer" {
set iso="/iso/debian-9.x-amd64-mini.iso"
loopback loop $iso
linux (loop)/linux
initrd (loop)/initrd.gz
}
# 16.x Xenial LTS - https://help.ubuntu.com/community/Installation/MinimalCD
menuentry "Ubuntu 16.04/Xenial LTS - 64bit Mini-Installer" {
set iso="/iso/ubuntu-16.04-mini-amd64.iso"
loopback loop $iso
linux (loop)/linux boot=casper iso-scan/filename=$iso noprompt noeject
initrd (loop)/initrd.gz
}
The main trick is the use of the loopback directive to directly use the iso, but other directives to the linux kernel may be required, such as iso-scan/opt=xxx. Unfortuantely, it's still a bit more of an art to know what's in the initrd image to know what things you can use to ensure the kernel has all the required bits. Also, sometimes it's helpful to examine the grub.cfg inside iso itself (which is otherwise not used in this setup) to see what options are typically passed to the kernel on boot.
# simplify future editing of grub with symlink to "root".
# works on Mac - unsure of magic.
# .. but not on Linux, since FAT* fs can't do symlinks.
$ cd /mnt/multiboot
$ ln -s grub/grub.cfg grub.cfg
# unmount the device
$ cd /mnt
$ umount /mnt/multiboot
Original idea came from http://www.circuidipity.com/multi-boot-usb.html, with other tips or ideas from:
- https://help.ubuntu.com/community/Grub2/ISOBoot (includes ideas to make it UEFI compatible)
- https://help.ubuntu.com/community/Grub2/ISOBoot/Examples
- http://askubuntu.com/questions/388382/multi-partition-multi-os-bootable-usb (UEFI notes)
- https://wiki.archlinux.org/index.php/Multiboot_USB_drive
- http://www.pendrivelinux.com/multiboot-create-a-multiboot-usb-from-linux/
- https://github.com/thias/glim
- http://chtaube.eu/computers/freedos/bootable-usb/
- https://wdullaer.com/blog/2010/02/26/boot-iso-files-from-usb-with-grub4dos/ (using
grub4dos)
Other tools/tips
Mounting ISO on (Mac) OSX, e.g. to examine embedded grub.cfg (source)
hdiutil attach -nomount DIST.iso
mkdir /tmp/DIST
mount -t cd9660 /dev/diskX /tmp/DIST
less /tmp/DIST/boot/grub/grub.cfg
...
umount /tmp/DIST
hdiutil detach diskX
Collection of random issues I've run into when using using this stick to build systems. Argueably, none of this is strictly related to the multiboot idea, but it's where I keep my notes and look for reminders/hints.
When installing Ubuntu 16.04 (or 18), with many LVM volumes (perhaps holding other OSes), the installation hangs at 66% "Installing GRUB boot loader".
Found this bug ref and this one too.
Workaround for me was to follow the instructions in the latter and when at the “Install the GRUB boot loader to the master boot record?” prompt in the installer, switch to a console (Alt-F2), and remove this file:
mv /target/etc/grub.d/30_os-prober /target/30_os-prober
This will prevent update-grub from running os-prober, which should avoid running into this issue. Of course, other operating systems won't be listed, but at least that should prevent the installation process from getting entirely stuck. After the reboot into the system, you can put back the os-prober script and try update-grub again.
When this occurs, something about installing grub failed to recognize the correct boot files to install. This post suggested a workaround to boot into a live instance (from your handy multiboot stick), mount the /boot partition (or root drive) and then reinstall grub. e.g.:
mount /dev/sda1 /mnt
grub-install /dev/sda --boot-directory=/mnt