Make ISO images hybrid and with GPT to improve compatability

[antongisli]

Kairos version:
3.0.9

CPU architecture, OS, and Version:
Dell optiplex 7050 (several years old)

Describe the bug
With trusted boot, does not recognize bootable USB stick (UEFI)

To Reproduce
just create TB install iso and try to boot off it, it will not be shown as bootable

Expected behavior
that the stick shows as a bootable device

Additional context
I managed to get it to work by modifying the ISO build command here:

kairos/Earthfile

Line 522 in 47b3d1c

RUN xorriso -as mkisofs -V 'UKI_ISO_INSTALL' -e efiboot.img -no-emul-boot -o $ISO_NAME.iso /tmp/efi

I changed it to:
xorriso -as mkisofs -V 'UKI_ISO_INSTALL' -e efiboot.img -no-emul-boot -isohybrid-gpt-basdat -isohybrid-mbr /usr/lib/ISOLINUX/isohdppx.bin -o test.iso /mnt/original_iso

Before running the above, I had to mount a generated ISO into /mnt/original_iso, and install isolinux + syslinux-common to get /usr/lib/ISOLINUX/isohdppx.bin:
sudo apt-get install isolinux syslinux-common

After this, the device shows as bootable on my dell.

[ci-robbot]

Hello antongisli, I'm a bot assisting with issue triage in the Kairos repository. Your issue has been labeled 'triage' to indicate that it has been reviewed and meets the basic requirements for further examination. Thank you for providing a clear description of the issue and the steps to reproduce it. It appears that you have already found a solution by modifying the ISO build command. As this is not a bug in the code itself, but rather a specific use case, it might be more appropriate to consider it as a feature request or customization rather than a bug report. Please feel free to open a new discussion or pull request if you'd like to propose changes to the ISO build process. Thank you for helping improve the Kairos project, and don't hesitate to ask if you have any further questions. I am an experiment of @mudler and @jimmykarily.

[Itxaka]

-isohybrid-gpt-basdat causes the creation of a partition of type 0xef in the MBR partition table. It also causes production of a GPT which stays invalid, nevertheless, because of the existence of the MBR partition. The MBR partition marks the -e boot image as EFI System Partition. This is needed for booting via EFI from USB stick.

Makes sense to me.

The ISO 9660 filesystem is then supposed to boot from optical media and from disk storage via BIOS and via UEFI. Unfortunately, there seem to be some UEFI implementations that boot from MBR and [fail to boot if GPT is present](http://wiki.osdev.org/Broken_UEFI_implementations#GIGABYTE_Hybrid_EFI). Therefore, some Linux distributions have special ISO images for amd64 containing only BIOS equipment.

xorriso can add the GPT equipment by its "-isohybrid-gpt-basdat" option: