Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions

[Thomas Schmitt]

Hi,

Florian Pelz wrote:
> I find a efi/boot/bootx64.efi PE executable inside efi.img on the Guix
> ISO. On Debian the long name is EFI/boot/bootx64.iso in capital letters

(I assume s/bootx64.iso/bootx64.efi/)

It's FAT filesystem. Upper case or lower case does not matter.
Most probably it is a matter of mount options whether you see capital
or small letters.
The image files seem to contain the names in capital letters:

  # mount guixsd-install-0.16.0.x86_64-linux.iso /mnt/iso

  $ strings /mnt/iso/efi.img | head -9
  MTOO4021
  Hf3NO NAME    FAT12
  EFI
  .
  ..
  BOOT
  .
  ..
  BOOTX64 EFI

  # umount /mnt/iso
  # mount debian-live-9.8.0-amd64-xfce.iso /mnt/iso

  $ strings /mnt/iso/boot/grub/efi.img | head -17
  mkfs.fat
  dNO NAME    FAT12
  This is not a bootable disk.  Please insert a bootable floppy and
  press any key to try again ...
  EFI
  KNKN
  .
  KNKN
  ..
  KNKN
  BOOT
  KNKN
  .
  KNKN
  ..
  KNKN
  BOOTX64 EFI


> How would I check if it gets run?

Interesting question. If it says "GRUB" or "Guix", then it runs. But up
to then it may start and fail silently.


> the Guix USB drive
> merely does not show up (for Debian, it shows up as an EFI partition
> in the boot menu).

So probably it is not run.

I'll develop a xorriso repack run for the layout of Debian ISOs, as
strange as it is.


Have a nice day :)

Thomas