[bug #55118] ISO file generation for testing a boot menu

[Markus Elfring]

URL:
  <https://savannah.gnu.org/bugs/?55118>

                 Summary: ISO file generation for testing a boot menu
                 Project: GNU GRUB
            Submitted by: elfring
            Submitted on: Tue 27 Nov 2018 05:01:33 PM CET
                Category: Booting
                Severity: Major
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 
                 Release: 2.02
         Reproducibility: Every Time
         Planned Release: None

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Details:

I would like to construct a boot menu (like the following) for the software
“GRUB 2.02-35.1”.


…
  menuentry 'GParted 0.32.0-1 (aus der SSHD-Boot-Partition)' --class Debian
--class Linux --class ISO {
    insmod part_msdos
    insmod ext2
    ISO=/ISO/gparted-live-0.32.0-1-amd64.iso
    search -f --set --no-floppy $ISO
    loopback xyz $ISO
    linux (xyz)/syslinux/isolinux.bin boot=live config union=aufs noswap
noprompt ip=frommedia findiso=/boot$ISO toram=filesystem.squashfs lang=de
keyboard=de
  }
…



I saw the message “error: invalid magic number”
<https://git.savannah.gnu.org/cgit/grub.git/tree/grub-core/loader/i386/linux.c?id=e8b37e2c8de7570ca9a6c7ba874762d8c4ba9373#n667>
after I selected such a boot menu entry.
But I determined from the display of a hex editor that the value “0xaa55”
<https://en.wikipedia.org/wiki/Master_boot_record#cite_note-NB_Magic_AA55-14>
should exist at the expected position in the referenced iso file.
* Now I am curious if a corresponding ISO file variant can be created so that
such a configuration can be tried out also by the execution of a virtual
machine (instead of writing the data to an other physical device before).
* Will it help to print a bit of extra information (like bytes from the failed
comparison) for easier software debugging?




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