Hi, Wouter Verhelst wrote: > This image however does not support booting on a UEFI-only system.
It does support EFI booting from CDROM. At least with qemu and OVMF as EFI firmware. > Is there anyone with the required knowledge who would be willing to > look into fixing that? I downloaded http://ftp.debian.org/debian/dists/sid/main/installer-amd64/current/images/netboot/mini.iso which bears this boot equipment: El Torito catalog : 59 1 El Torito cat path : /boot.cat El Torito images : N Pltf B Emul Ld_seg Hdpt Ldsiz LBA El Torito boot img : 1 BIOS y none 0x0000 0x00 4 268 El Torito boot img : 2 UEFI y none 0x0000 0x00 832 60 El Torito img path : 1 /isolinux.bin El Torito img opts : 1 boot-info-table isohybrid-suitable El Torito img path : 2 /boot/grub/efi.img MBR partition table: N Status Type Start Blocks MBR partition : 1 0x80 0x17 0 51200 MBR partition : 2 0x00 0x01 51200 12288 I.e. it has an EFI boot image for booting from CD, but no partition of MBR type 0xef which would point to that image file /boot/grub/efi.img. So expectably it boots by qemu-system-x86_64 -enable-kvm -m 512 -bios /usr/share/ovmf/OVMF.fd -cdrom mini.iso and does not boot by qemu-system-x86_64 -enable-kvm -m 512 -bios /usr/share/ovmf/OVMF.fd -hda mini.iso One could use xorriso to repack the ISO and apply options which would cause production of partition tables. But in this case we have the classical situation for SYSLINUX program "isohybrid". (We even have the repaired version in Sid, which does not write random chinese GPT partition names.) isohybrid -u mini.iso This yields a partition table layout similar to netinst: MBR partition table: N Status Type Start Blocks MBR partition : 1 0x80 0x00 0 63488 MBR partition : 2 0x00 0xef 240 832 MBR partition path : 2 /boot/grub/efi.img GPT : N Info GPT disk GUID : 12f7657a83abeb4a8a7290afeb748d8d GPT entry array : 2 128 overlapping GPT lba range : 34 63454 63487 GPT partition name : 1 490053004f004800790062007200690064002000490053004f00 GPT partname local : 1 ISOHybrid ISO GPT partition GUID : 1 b028cc51ece2734982f7a619cd3b977a GPT type GUID : 1 a2a0d0ebe5b9334487c068b6b72699c7 GPT partition flags: 1 0x0000000000000000 GPT start and size : 1 0 50464 GPT partition name : 2 490053004f00480079006200720069006400 GPT partname local : 2 ISOHybrid GPT partition GUID : 2 3e7e8dac6a466b488fec85bd1f82f267 GPT type GUID : 2 a2a0d0ebe5b9334487c068b6b72699c7 GPT partition flags: 2 0x0000000000000000 GPT start and size : 2 240 832 GPT partition path : 2 /boot/grub/efi.img If i run again qemu-system-x86_64 -enable-kvm -m 512 -bios /usr/share/ovmf/OVMF.fd -hda mini.iso i see a few messages about failed attempts. But then i get to the GRUB2 menu. Actually the GPT is considered surplus. Any UEFI compliant firmware should follow the lure in MBR partition 0xef, because the GPT is not announced by MBR having a single partition of type 0xee. Have a nice day :) Thomas
