• nl6720's avatar
    Move FAT image to a separate partition outside the ISO 9660 file system · 729d16b4
    nl6720 authored
    Support bios.syslinux.eltorito boot mode without bios.syslinux.mbr.
    bios.syslinux.mbr does not work without bios.syslinux.eltorito because -isohybrid-mbr requires the El Torito boot image.
    
    Support uefi-x64.systemd-boot.esp boot mode without uefi-x64.systemd-boot.eltorito and vice versa.
    If uefi-x64.systemd-boot.eltorito is used without uefi-x64.systemd-boot.esp, the El Torito boot image will be placed in the ISO 9660 file system as before.
    Note that an ISO created with only uefi-x64.systemd-boot.eltorito will still be bootable as a "hard disk" on OVMF. OVMF will boot the El Torito image.
    
    This change has the following effect on the partition tables:
    
    - *.eltorito options add El Torito boot catalog entries. MBR and GPT are not affected.
    - uefi-x64.systemd-boot.esp creates a protective MBR partition table and a GPT table that includes a Linux filesystem data partition for the ISO 9660 volume, an EFI system partition and a Microsoft basic data partition that maps the 300 KiB padding added by xorriso.
    - bios.syslinux.mbr (without uefi-x64.systemd-boot.esp): adds a MBR partition table and maps the ISO 9660 volume as a partition of type 0x83. No GPT is produced.
    - bios.syslinux.mbr (with uefi-x64.systemd-boot.esp): adds an second partition in the MBR (after 0xEE) starting from sector 0 to sector 1 with type 0 and marks it as bootable. This violates the GPT specification, but allows some systems to succesfully boot in BIOS mode from GPT.
    
    Fixes #49
    729d16b4