This is a simple note for people who are googling this topic right now, and you are welcome.


  • Legacy BIOS needs bootloaders to be installed into MBR and the reserved space after it.

  • UEFI only needs bootloaders in ESP(EFI System Partition).

  • There is no resource competition between legacy BIOS and UEFI requirements.


  • grub-pc-bin and grub-efi-amd64-bin packages for Debian users.

  • An USB storage stick, MBR or GPT. Some unallocated space(1MB is enough) at the beginning of disk if you are using GPT.

  • A vfat partition with the “boot” flag.


# mount /dev/sdb1 /media/sdb1

# grub-install --target=i386-pc --boot-directory=/media/sdb1/boot /dev/sdb

# grub-install --target=x86_64-efi --efi-directory=/media/sdb1/ --boot-directory=/media/sdb1/boot --removable /dev/sdb

Configuration(just a template)

# /media/sdb1/boot/grub/grub.cfg
set root=(hd0,1)

menuentry "FreeDOS" {
        linux16  /boot/freedos/memdisk
        initrd16 /boot/freedos/balder10.img
menuentry "Memtest86+" {
        loopback loop /boot/systemrescuecd-x86-x.y.z.iso
        linux16 (loop)/bootdisk/memtestp
menuentry "Ubuntu xx.yy" {
        set isofile="/boot/ubuntu-xx.yy-desktop-amd64.iso"
        loopback loop $isofile
        linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile noprompt noeject
        initrd (loop)/casper/initrd.lz
menuentry "SystemRescueCd" {
        set isofile="/boot/systemrescuecd-x86-x.y.z.iso"
        loopback loop $isofile
        linux   (loop)/isolinux/rescue64 docache isoloop=$isofile
        initrd  (loop)/isolinux/initram.igz
menuentry "Install Debian GNU/Linux" {
        linux   /boot/debian/vmlinuz priority=low recommends=false
        initrd  /boot/debian/initrd.gz
menuentry "Debian GNU/Linux Rescue Mode" {
        linux   /boot/debian/vmlinuz priority=low recommends=false rescue/enable=true
        initrd  /boot/debian/initrd.gz

Done, enjoy fixing others’ computers then, which I already quit :D