[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Putting It All On a Stick



Hi,

Steve Matzura wrote:
> How would I know for sure if it's ISO hybrid, 

A strong indication is the presence of partitions when inquired
by program fdisk.

  $ /sbin/fdisk -l debian-8.2.0-amd64-BD-1.iso
  ...
  debian-8.2.0-amd64-BD-1.iso1 *        0 43859651 ...
  ...

You may let xorriso report

  $ xorriso -indev debian-8.2.0-amd64-BD-1.iso -toc 2>&1 | \
    grep '^Boot record  :'

Depending on the version you will get

  Boot record  : El Torito , ISOLINUX boot image capable of isohybrid
or
  Boot record  : El Torito , ISOLINUX isohybrid MBR pointing to boot image
or
  Boot record  : El Torito , MBR isohybrid cyl-align-off GPT APM

The first message (from xorriso-1.2.2) indicates isohybrid only if
fdisk reports about partitions in the ISO.
The younger versions 1.3.2 (Debian stable) and 1.4.2 (Sid) can
tell without help by others.

xorriso-1.4.2 can list the whole boot equipment

  $ xorriso -indev debian-8.2.0-amd64-BD-1.iso \
    -report_system_area plain -report_el_torito plain

which will report
  ...
  Boot record  : El Torito , MBR isohybrid cyl-align-off GPT APM
  Media summary: 1 session, 10964913 data blocks, 20.9g data,  750g free
  Volume id    : 'Debian 8.2.0 amd64 1'
  System area options: 0x00000202
  System area summary: MBR isohybrid cyl-align-off GPT APM
  ISO image size/512 : 43859652
  Partition offset   : 0
  MBR heads per cyl  : 0
  MBR secs per head  : 0
  MBR partition table:   N Status  Type        Start       Blocks
  MBR partition      :   1   0x80  0x00            0     43859652
  MBR partition      :   2   0x00  0xef        75632          832
  MBR partition path :   2  /boot/grub/efi.img
  GPT                :   N  Info
  GPT disk GUID      :      e68c59d8e9e83949b42975afc9d12f0f
  GPT entry array    :      12  208  overlapping
  GPT lba range      :      64  43859598  43859651
  GPT partition name :   1  490053004f00480079006200720069006400
  GPT partname local :   1  ISOHybrid
  GPT partition GUID :   1  e68c59d8e9e83949b42b75afc9d12f0f
  GPT type GUID      :   1  a2a0d0ebe5b9334487c068b6b72699c7
  GPT partition flags:   1  0x1000000000000001
  GPT start and size :   1  0  43859596
  GPT partition name :   2  490053004f004800790062007200690064003100
  GPT partname local :   2  ISOHybrid1
  GPT partition GUID :   2  e68c59d8e9e83949b42a75afc9d12f0f
  GPT type GUID      :   2  a2a0d0ebe5b9334487c068b6b72699c7
  GPT partition flags:   2  0x1000000000000001
  GPT start and size :   2  75632  832
  GPT partition path :   2  /boot/grub/efi.img
  APM                :   N  Info
  APM block size     :      2048
  APM gap fillers    :      0
  APM partition name :   1  EFI
  APM partition type :   1  Apple_HFS
  APM start and size :   1  18908  208
  APM partition path :   1  /boot/grub/efi.img
  El Torito catalog  : 18907  1
  El Torito cat path : /isolinux/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       19116
  El Torito boot img :   2  UEFI  y   none  0x0000  0x00    832       18908
  El Torito img path :   1  /isolinux/isolinux.bin
  El Torito img opts :   1  boot-info-table isohybrid-suitable
  El Torito img path :   2  /boot/grub/efi.img


> and how would it fit on a standard 16GB drive?

It would not. If you cut of the tail you will get i/o errors when
files shall be read which are stored in the cut-off part.
The files are not sorted by importance or popularity in the ISO.


> I strongly suspect that's true
> because  the temp file that was created as soon as the process started
> was expanded to 20.9GB and never changed, so it's probably full of a
> lot of 0's toward the end.

No. It is packed full with compressed .deb files (and a few others).

In the beginning of Jigdo download the 20+ GB mainly consists of holes,
indeed. But the dowloading of .deb files fills each of the holes.

Jigdo = Jigsaw puzzle Download
The .template file is like the wooden frame for a kindergarten jigsaw toy.
The .deb files (and some others) are the wooden blocks which fit into
the holes.
The .jigdo file substitutes for the toddler's brain.
  http://lcdn.jigsawpuzzleshoppe.com/media/easyslide/wooden-jigsaw-puzzles.png


Have a nice day :)

Thomas


Reply to: