Re: Debian release not opening

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Dave wrote:
> i have downloaded debian-9.4.0-amd64-DVD-1.iso
> when i double click on it, it says cannot open. the iso
> debian-9.4.0-amd64-DVD-2 and iso debian-9.4.0-amd64-DVD-3
> i can open and read. the same thing happened with debian 9.0.0.
> i am using mac pro 10.10.5  to download / open / and hopefully burn.

While waiting for the ISO to arrive, i dig in old memories.

Several years ago, there was a report about an i386 DVD-1 on Mac
"Snow Leopard":
  https://lists.debian.org/debian-cd/2011/04/msg00029.html

Proposal to remove USB stick equipment:
  https://lists.debian.org/debian-cd/2011/04/msg00040.html

Confirmation of success:
  https://lists.debian.org/debian-cd/2011/04/msg00042.html

Proposal of quicker workaround:
  https://lists.debian.org/debian-cd/2011/04/msg00045.html

Beginning theory about partition offset 16:
  https://lists.debian.org/debian-cd/2011/04/msg00060.html
Confirmation (?) of that theory:
  https://lists.debian.org/debian-cd/2011/04/msg00061.html
It once even had an Apple Bug Id:
  https://lists.debian.org/debian-cd/2011/04/msg00066.html

Partition offset 16 was later disabled in debian-cd because of a xorriso
bug which has been fixed soon after. So i wonder ...

Ah. Download completed.

  $ xorriso -indev debian-9.4.0-amd64-DVD-1.iso -report_system_area plain
  ...
  Partition offset   : 0
  ...

So this time it is not about partition offset.
Nevertheless, it is worth a try to zeroize the image part with the
boot entry points for USB stick: MBR, pseudo-GPT, Apple Partition Map.
The quick way is:

  # Make backup of USB boot equipment
  dd if=debian-9.4.0-amd64-DVD-1.iso bs=2048 count=16 \
     of=debian-9.4.0-amd64-DVD-1.system_area

  # Overwrite USB boot equipment by zero-bytes
  dd if=/dev/zero bs=2048 count=16 conv=notrunc of=debian-9.4.0-amd64-DVD-1.iso

The resulting ISO image is supposed to still boot from DVD.
But if you want to boot it by the Mac, nothing is for sure.

Better first try with the unaltered ISO image.
(When booting Debian, the quirks of MacOS are inconsequential.)


Have a nice day :)

Thomas