Re: ISO installer image: GPT versus MBR partitions

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

Hi,

Florian Pelz wrote:
> So what’s the plan?
> Wait for another responce from the grub-devel mailing list?

They need time to to make up their mind. Maybe other incidents are needed to
push towards some change in grub-mkrescue.
We have a halfways positive response from the old owner and a somewhat
uninformed response from the new manager, indicating between the lines
that he is too busy with other things currently.


> Package grub-mkrescue-sed.sh and use
> --xorriso=/path/to/grub-mkrescue-sed.sh when calling grub-mkrescue?

It is part of the libisoburn release tarball, from where Guix gets its
xorriso, afaik. It is also part of the GNU xorriso tarball, which builds
a static compilation of libburn, libisofs, libisoburn, and libjte.

Problem is that for the EFI partition fix, you need the current development
version. The partition definitions should be ok with the released version
1.5.0.
I plan a new release this year, but not right now.

How comfortable is the Guix patching system ? :))

  "New control variable for grub-mkrescue-sed.sh: MKRESCUE_SED_IN_EFI_NO_PT"
  https://dev.lovelyhq.com/libburnia/libisoburn/commit/3a2a3ba737a06162c22ace0ae09d33ba97aa2673

  "grub-mkrescue-sed.sh: MKRESCUE_SED_IN_EFI_NO_PT="extra"
   to erase MBR signature"
  https://dev.lovelyhq.com/libburnia/libisoburn/commit/1eb51f44dadb8b6c5f87533ca357186cdc1ac625

(The holidays are over. Our certificate works again.)


Looking at a commit from 2 years ago (i.e. in released version)
  "Made -iso_mbr_part_type 0x00 default of grub-mkrescue-sed.sh
   mode "mbr_only""
i remember that there was an EFI reported on grub-devel which strictly
refused on anything but a single MBR partition for EFI. So the camouflage
trick of partition type 0x0 was necessary for the ISO partition.

This is quite contrary to the expectations of partition editors, though.
I deem this EFI's behavior a much clearer bug than the Macbook EFI's.
So i stay with my proposal of native xorriso command
  -boot_image any iso_mbr_part_type=0x83
or mkisofs emulation option
  -iso_mbr_part_type 0x83

(To my knowledge, the Guix xorriso run switches from mkisofs emulation
 to native commands by "--". So -boot_image would be the one to use
 if it gets appended to the other arguments.)


> Add an option to “guix system disk-image” to select which
> grub-mkrescue-sed.sh environment variables to enable?

This would be great.
(I was brought up with HP BASIC and never was able to solve the Lisp
 puzzles in german magazine Bild der Wissenschaft of the 1980s.
 So i cannot help much with translating the usage gestures or even
 the script itself from shell to Guile.)


Have a nice day :)

Thomas