How To Create Multi-boot USB Drive Without Ventoy – GRUB FTW

Why GRUB

GRUB is the standard Linux bootloader for decades, and also supports other operating systems. Ventoy, another popular Open Source tool made by Chinese developer Hailong Sun, does the job really straightforward and doesn’t need any dancing with configs. So, why do we still need Grub? There are several reasons:

• "Do not reinvent the wheel"
• Never–ending positive virus scans
• Secure Boot: Ventoy still loads unsigned executables
• Ventoy problems with Dell laptops

GRUB2 supports more file systems like Btrfs and F2FS and much more configuration options. Next use cases are possible:

• all files on single partition – easy to use
• all iso images can be located in one directory
• add/delete images is easy – the file tree under user control

How to install

Detect the target device by size:

$ fdisk -l

Create a new partition table if needed:

# parted /dev/sdX(parted) mklabel msdos

Create new partition:

For BIOS/MBR:(parted) mkpart primary vfat 4MiB 100%(parted) set 1 boot on

Install Grub2:

# mount /dev/sdX /mnt# mkdir /mnt/boot# BIOS# grub2-install --target=i386-pc --recheck --boot-directory=/mnt/boot /dev/sdX# UEFI# grub2-install --target x86_64-efi --efi-directory /mnt --boot-directory=/mnt/boot --removable

Now we can copy the images to a flash drive, they can be located anywhere.

$ ls -a /mnt/boot/*iso/mnt/boot/elementaryos.iso/mnt/boot/Fedora.iso/mnt/boot/linuxmint.iso/mnt/boot/tails.iso/mnt/boot/ubuntu.iso

And setup the Grub2 config:

cat /boot/grub2/grub.cfg# /boot/grub/grub.cfg - Grub2 configinsmod part_msdosinsmod part_gptinsmod ext2insmod iso9660insmod fat# Get UUID of USB Flash with `$ lsblk -f` command:# 56f48195-f142-4df4-84cf-5a21f29177c4search --no-floppy --fs-uuid --set=root 56f48195-f142-4df4-84cf-5a21f29177c4menuentry 'Ubuntu' {	set isofile='/boot/ubuntu.iso'	loopback loop $isofile	linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile locale=en_US.UTF-8	initrd (loop)/casper/initrd.lz}menuentry 'elementaryos' {	set isofile='/boot/elementaryos.iso'	loopback loop $isofile	linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile locale=en_US.UTF-8	initrd (loop)/casper/initrd.lz}menuentry "Linux Mint" {    set iso=/boot/linuxmint.iso    loopback loop $iso    linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$iso noeject noprompt    initrd (loop)/casper/initrd.lz}menuentry "Tails" {    set isofile='/boot/tails.iso'    loopback loop $isofile    linux (loop)/live/vmlinuz2 boot=live config findiso=${isofile} live-media=removable apparmor=1 security=apparmor nopersistent noprompt timezone=Etc/UTC block.events_dfl_poll_msecs=1000 noautologin module=Tails    initrd (loop)/live/initrd2.img}	menuentry 'Fedora Workstation' {	set isofile='/boot/Fedora.iso'	loopback loop $isofile	linux (loop)/isolinux/vmlinuz0 root=live:CDLABEL=Fedora-Live-WS-x86_64 iso-scan/filename=$isofile rd.live.image	initrd (loop)/isolinux/initrd0.img}

Now time to unmount the flash drive and reboot for testing.

Hard cases with non-popular images

Sometimes there’s a task to boot not popular image and Internet isn’t helpful. The only one way is to dive deeper into the image itself and figure it out.

• isoscan/filename – we need the path for image boot menu.
• linux ... – unique additional boot parameters.

Let’s mount the iso image and check the configuration we need for a successful boot:

$ sudo mount -o loop /path/to/iso /mnt/

isolinux or boot/isolinux are two popular locations to check boot configuration. We need something like

label livemenu label Try Ubuntu without installingkernel /casper/vmlinuz.efiappend file=/cdrom/preseed/ubuntu.seed boot=casperinitrd=/casper/initrd.lz quiet splash

The kernel parameter contains the Linux option for the linux (loop)..., the same with initrd path. append file should be added to linux (loop)... line.

Some Linux distributions use a parameter isolabel, it can be obtained from isoinfo command output: isoinfo -d -i image.iso.

Projects related to GRUB multi-boot

• Glim, a set of grub configuration files to turn a simple VFAT-formatted USB memory stick with many GNU/Linux distribution, supports Antergos, Antix, Arch, Bodhi, Centos, Clonezilla, Debian, Elementary, Fedora, IPXE, Kali, Linuxmint, Manjaro, Ubuntu, Void and more.
• AIO Boot – All-in-One bootable software for USB and HDD, supports Clover, rEFInd, Grub4Dos, Enoch Chameleon and Syslinux. Many Windows and Linux images are supported too.