Hi, Dusty Mabe wrote: > Currently we use isohybrid [1] (also from syslinux package) to modify the > ISO to be able to be booted on a USB key. Would we be able to still get that > functionality without isohybrid from the syslinux package? Yes. The GRUB2 MBR code will get the equivalent treatment already when the ISO image gets created. A postprocessing run will not be needed for getting the ability to boot from USB stick. The ESP will be marked by an entry in a GPT partition table. But some BIOS implementations might not recognize the bootability of the stick when pure GPT is used. We have the example of Dell XPS 15 L502X which is not fully explored yet. GRUB2 development encountered other machines which did not boot if not some MBR partition beared the boot/active flag. This is not particularly a GRUB problem. But the isohybrid program of ISOLINUX always creates a MBR partition with boot/active flag. The price is that isohybrid never produces a valid GPT. > https://github.com/coreos/coreos-assembler/blob/b8f61207c7a4ce345a1f136823dac6c628086273/src/cmd-buildextend-live#L642 Insofar the comment in line 639 of src/cmd-buildextend-live is not fully correct: "Add MBR, and GPT with ESP, ..." The ESP is marked by isohybrid --uefi in a UEFI compliant way in the MBR partition table as partition of type 0xEF. isohybrid creates a GPT indeed. But is is not valid because not announced by a MBR partition of type 0xEE. Further the GPT partition entry which marks the ESP does not have the prescribed type GUID for EFI, but rather the type GUID for a Microsoft basic data partition. The new partition layout in boot-grub2-f36.iso would make the comment fully correct: The GPT is valid and the ESP entry has the right type GUID. But then you would have to disable the run of /usr/bin/isohybrid and thus need no comment at all. You would also have to switch from genisoimage to xorrisofs in the "x86_64" case. Several options would have to be changed. Have a nice day :) Thomas _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
