Re: [Bug-xorriso] Mountable ISO and GRUB2

[Thomas Schmitt]

Hi,

Carlo Caione wrote:
> -isohybrid-mbr  empty.mbr -b boot/grub/i386-pc/eltorito.img

This will not work because the -isohybrid-mbr feature wants to see the
magic number of isolinux.bin in the -b file. Then it patches the address
of the isolinux.bin file into the MBR x86 code at byte 432 to 439 so that
code execution hops onto the isolinux.bin boot image.
Lots of ISOLINUX specifics in there.

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There is nevertheless prepared an mjg-like layout in grub-mkrescue-sed.sh

  export MKRESCUE_SED_MODE=mjg
  export MKRESCUE_SED_PROTECTIVE=no
  export MKRESCUE_SED_PARTNO=2
  grub-mkrescue -o output.iso minimal --xorriso=/home/.../grub-mkrescue-sed.sh

This yields

  System area summary: MBR grub2-mbr cyl-align-off GPT APM
  ISO image size/512 : 24436
  Partition offset   : 0
  MBR heads per cyl  : 64
  MBR secs per head  : 32
  MBR partition table:   N Status  Type        Start       Blocks
  MBR partition      :   1   0x80  0x83            0        24436
  MBR partition      :   2   0x00  0xef        24436         5760
  GPT                :   N  Info
  GPT disk GUID      :      39461e450154884aa4babdf2f2404792
  GPT entry array    :      16  192  separated
  GPT lba range      :      64  30198  30247
  GPT partition name :   1  48004600530050004c0055005300
  GPT partname local :   1  HFSPLUS
  GPT partition GUID :   1  39461e450154884aa4bbbdf2f2404792
  GPT type GUID      :   1  005346480000aa11aa1100306543ecac
  GPT partition flags:   1  0x1000000000000001
  GPT start and size :   1  336  24100
  GPT partition name :   2  490053004f004800790062007200690064003100
  GPT partname local :   2  ISOHybrid1
  GPT partition GUID :   2  39461e450154884aa4b8bdf2f2404792
  GPT type GUID      :   2  a2a0d0ebe5b9334487c068b6b72699c7
  GPT partition flags:   2  0x1000000000000001
  GPT start and size :   2  24436  5760
  APM                :   N  Info
  APM block size     :      2048
  APM gap fillers    :      0
  APM partition name :   1  HFSPLUS_Hybrid
  APM partition type :   1  Apple_HFS
  APM start and size :   1  84  6025
  APM partition name :   2  Appended2
  APM partition type :   2  Data
  APM start and size :   2  6109  1440

The decisive option for getting mjg without ISOLINUX software is
  -part_like_isohybrid

The trick to get a mountable NBR partition is to append the EFI partition
as number 2.

The xorriso arguments are:

  -as mkisofs 
  -o output.iso -r
  -graft-points -no-pad
  --sort-weight 0 / --sort-weight 1 /boot

  --grub2-mbr /usr/lib/grub/i386-pc/boot_hybrid.img

  -part_like_isohybrid
  -append_partition 2 0xef /tmp/grub-mkrescue-sed-efi-img.32559 

  -hfsplus -apm-block-size 2048
  -hfsplus-file-creator-type chrp tbxj /System/Library/CoreServices/.disk_label
  -hfs-bless-by i /System/Library/CoreServices/boot.efi

  --modification-date=2016122712245900

  -b boot/grub/i386-pc/eltorito.img
     -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info
  -eltorito-alt-boot
  -e --interval:appended_partition_2:all::
     -no-emul-boot -isohybrid-gpt-basdat
  /tmp/grub.8niQjo minimal

The file
  /tmp/grub-mkrescue-sed-efi-img.32559
is the efi.img file prepared by grub-mkrescue and moved out of directory
  /tmp/grub.8niQjo
by grub-mkrescue-sed.sh so that it gets not as file into the ISO.

----------------------------------------------------------------------

I am now testing a new mode "gpt_appended" which produces a pure GPT
layout with Protective MBR and mountable ISO filesystem in GPT partition 1.
(No overlapping partitions, of course.)

Decisive are two options added to the "mbr_only" proposal: 
  -partition_offset 16
  -appended_part_as_gpt

It already works with xorriso >= 1.4.4 but some fine tuning is necessary to
improve it and prepare -report_system_area "as_mkisofs" for properly
proposing reproduction options.


Have a nice day :)

Thomas