Thanks very much for the analysis, Thomas! > There remain riddles:
> Why does the grub-mkrescue ISO not boot on V14IIL ? > (I still wonder which other ISOs boot on that machine.) > Why did the old Ubuntu ISOs with their invalid GPT boot on sudodus' V130 > whereas a similarly invalid GPT did not help with the 20201007.1 ISO ? Yes, that is puzzling. > Maybe Canonical Ltd. should ask Lenovo Group Limited for enlightenment. I've escalated it internally to the right team, and they will follow up, but no guarantees we'll get a meaningful answer :) > ------------------------------------------------------------------------- > The xorrisofs option to cause GPT during the production of an Ubuntu ISO > would be > -appended_part_as_gpt Thinking it through, I am happy for us to make this change from MBR to GPT. - optical media don't care about the partition table, only the El-Torito boot image. - BIOS boot of USB doesn't care about the partition table, only the MBR - UEFI 2.0 requires systems to understand GPT - pre-2.0 UEFI systems are mostly not guaranteed to work anyway. I've made this switch now and confirmed the result at <http://cdimage.ubuntu.com/ubuntu/daily-live/20201009.1>. I do see that the GPT has an extra partition at the end; is this required for alignment? I haven't seen such partition entries when using MBR. $ gdisk -l ~/devel/iso/groovy-desktop-amd64.iso GPT fdisk (gdisk) version 1.0.5 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Disk /home/vorlon/devel/iso/groovy-desktop-amd64.iso: 5736268 sectors, 2.7 GiB Sector size (logical): 512 bytes Disk identifier (GUID): 8897A8AA-43A3-4BD4-A4AA-C472E4376703 Partition table holds up to 248 entries Main partition table begins at sector 2 and ends at sector 63 First usable sector is 64, last usable sector is 5736204 Partitions will be aligned on 4-sector boundaries Total free space is 1 sectors (512 bytes) Number Start (sector) End (sector) Size Code Name 1 64 5725651 2.7 GiB 0700 ISO9660 2 5725652 5735603 4.9 MiB EF00 Appended2 3 5735604 5736203 300.0 KiB 0700 Gap1 $ Here is the full commandline used to construct this image. xorriso -as mkisofs -r -checksum_algorithm_iso md5,sha1 -V Ubuntu\ 20.10\ amd64 -o /srv/cdimage.ubuntu.com/scratch/ubuntu/groovy/daily-live /debian-cd/amd64/groovy-desktop-amd64.raw -J -joliet-long -l -b boot/grub/i386-pc/eltorito.img -no-emul-boot -boot-load-size 4 -boot- info-table --grub2-boot-info --grub2-mbr cd-boot-images/usr/share/cd- boot-images-amd64/images/boot/grub/i386-pc/boot_hybrid.img -append_partition 2 0xef cd-boot-images/usr/share/cd-boot-images- amd64/images/boot/grub/efi.img -appended_part_as_gpt -eltorito-alt-boot -e --interval\:appended_partition_2\:all\:\: -no-emul-boot -partition_offset 16 cd-boot-images/usr/share/cd-boot-images-amd64/tree CD1 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1886148 Title: failure to boot groovy daily To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1886148/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
