How to make a UEFI compatble ISO with grub-mkrescue?

Question

I have been following this guide to produce a customized version of Ubuntu.

As of now, the structure of the CD is complete. I just have to generate a bootable ISO image with the command:

sudo grub-mkrescue -o live_cd.iso /path/to/cd/root

I got a perfectly working iso image which boots well in VirtualBox, under UEFI mde.

The problem is when I copy the iso to my USB flash drive (using dd command) it does not boot in my real machine under UEFI mode. I get this:

However, I can boot the flash drive fine in legacy bios mode.
I have installed grub-efi package as well.

Can anyone tell me what I'm doing wrong?
Thanks!

Answer 1

1. mount Stick

   sudo mount -t vfat /dev/sdX /mnt

2. Install another Grub2 to USB:

   sudo grub-install --no-floppy --force --root-directory=/mnt /dev/sdX

3. Copy iso to stick

   cp -v ~/live-cd.iso /mnt

4. Add following to /mnt/boot/grub/grub.cfg

   set default="0"
   set timeout=10
   
   insmod fat
   set iso_path=/live-cd.iso
   loopback loop (${usb})${iso_path}
   set root=(loop)
   set bootopts="boot=casper iso-scan/filename=${iso_path} noprompt"
   
   menuentry "Boot ISO from HDD/USB" {
   linux (loop)/casper/vmlinuz $bootopts
   initrd (loop)/casper/initrd.img
   }
   

Source: https://help.ubuntu.com/community/MakeALiveCD/DVD/BootableFlashFromHarddiskInstall#Appendix_2._How_to_Make_bootable_USB_flash

It may solve your problem