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Re: Test Proposal for [bug #46716] Protective MBR partition is not marke

From: Thomas Schmitt
Subject: Re: Test Proposal for [bug #46716] Protective MBR partition is not marked as bootable
Date: Mon, 21 Dec 2015 18:37:05 +0100


first a helper in case repacking goes on with other ISOs.
To obtain the value for --modification-date= , do:

  $ xorriso -indev minimal-grub2.iso -pvd_info 2>/dev/null | \
      grep '^Modif\. Time  :' | sed -e 's/^Modif. Time  : //'

> https://goo.gl/photos/GRS5khE8r7Xgat9L8

A dedicated user of Apple electronics. :))
Do i get the USB symbol right that the image was presented on USB stick ?

I wonder how the machine came to "Windows".
This might be the HFS+ filesystem advertised by APM partition 2.

The first "EFI Boot" is possibly the MBR partition 1, which
your patching advertises as bootable but isn't by HDD habits.
But i wonder from where that "grub rescue>" started.
Maybe the Apple EFI offers the El Torito boot image /efi.img here
which contains GRUB2.

The second "EFI Boot" is probably MBR partition 2 of type 0xef.

> OK, the 2007 Mac does not recognize any of the isos below.

That's still the original one from grub-mkrescue, i assume.

> The 2012 Mac shows two working "EFI Boot" options on this ISO:

Seems to like type 0x00 and start LBA 1 better than 0x83 and LBA 0.
One should try which of the two differences does the trick.

But still not clear what GRUB2 is started by that first "EFI Boot"
offer. Obviously it gets confused by the mountable partition 1
of type 0x83.

To let the partition 1 start at LBA 1 even if no -hfsplus is given,
add option  --protective-msdos-label  to your repack run.

Oh ... without -hfsplus this keeps you from the plight of patching.
Directly out of xorriso:

  MBR partition table:   N Status  Type        Start       Blocks
  MBR partition      :   1   0x80  0xcd            1        31619
  MBR partition      :   2   0x00  0xef        31620         5760

Because --protective-msdos-label is an option meant for GRUB2
and no GPT is present (or suspected), this produces partition 1
in GRUB2 BIOS-only style. With boot flag.

The command was

  xorriso-1.3.2 -as mkisofs \
     -o /dvdbuffer/minimal-grub2-repacked.iso \
     -r \
     --modification-date='2015121916023100' \
     --grub2-mbr /dvdbuffer/minimal-grub2.mbr \
     -c '/boot.catalog' \
     -b '/boot/grub/i386-pc/eltorito.img' \
        -no-emul-boot -boot-load-size 4 -boot-info-table --grub2-boot-info \
     -eltorito-alt-boot \
     -e '/efi.img' \
        -no-emul-boot \
     -append_partition 2 0xef /mnt/iso/efi.img \
     -no-pad \
     --protective-msdos-label \

Have a nice day :)


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