I am attempting to create a custom Ubuntu 16.04 LTS Server installation media and have been following the instruction here https://help.ubuntu.com/community/InstallCDCustomization

When I attempt to run the commands:

# Hybrid/UEFI

xorriso -as mkisofs -r -V "Jeremys" \
        -J -l -b isolinux/isolinux.bin \
        -c isolinux/boot.cat -no-emul-boot \
        -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
        -eltorito-alt-boot \
        -e boot/grub/efi.img \
        -isohybrid-gpt-basdat \
        -boot-load-size 4 -boot-info-table \
        -o $IMAGE $BUILD

I get the following:

xorriso 1.4.2 : RockRidge filesystem manipulator, libburnia project.

Drive current: -outdev 'stdio:/opt/jeremy-uefi.iso'
Media current: stdio file, overwriteable
Media status : is blank
Media summary: 0 sessions, 0 data blocks, 0 data, 31.8g free
Added to ISO image: directory '/'='/opt/cd-image'
xorriso : UPDATE : 2963 files added in 1 seconds
xorriso : UPDATE : 2963 files added in 1 seconds
libisofs: FAILURE : Invalid image size 2368 Kb. Must be one of 1.2, 1.44or 2.88 Mb
libisofs: FAILURE : Trying to use an invalid file as boot image
xorriso : FAILURE : Could not attach El-Torito boot image to ISO 9660 image
xorriso : NOTE : -return_with SORRY 32 triggered by problem severity FAILURE

I have tracked the issue down to the boot/grub/efi.img image. However, after fighting with it all day, I haven't been able to get around it.

The obvious solution would be to make a new fat16 file system that is 2.88 Mb and copy the contents of the efi.img over to it, and substitute the original file. But it begs the question, how was the original Ubuntu CDs made?

  • 1
    Captcha does not let me post answers. So as comment: "-boot-load-size 4 -boot-info-table" must be written before "-eltorito-alt-boot", because they are meant as modifying options for "-b". After "-eltorito-alt-boot" comes the realm of "-e". There you need another option "-no-emul-boot" (as with "-b") in order to avoid the error message about floppy emulation sizes. But do not use "-boot-load-size" or "-boot-info-table" for the EFI image. Dec 27, 2018 at 9:21
  • Thank you! That appears to have fixed it. I am still surprised by how many articles are online that have it wrong.
    – Jeremy
    Dec 27, 2018 at 15:10
  • A community wiki hosted on the official Ubuntu help site should not be that wrong. I applied for editing permission, but the waiting queue is long. So i am preparing a mail to bother the wiki group owner and the most recent change author. Dec 27, 2018 at 16:13
  • @ThomasSchmitt if you're still active, can you post that as an answer?
    – ave
    Feb 24, 2020 at 13:11


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