Re: USB media install has wrong partition
Thomas,
Thank you for clarification on the layout, as it is in fact most helpful
in understanding GPT cruft. As a Gentoo user, I can in fact boot
system-rescue-cd and Knoppix as EFI USB. Sadly, this seems like one
more nail in the coffin of reasons I need to upgrade my PC. I cannot
reproduce the boot error on a dell system either.
Thank you for your support and time.
On Sat, Sep 15, 2018 at 07:09:58PM +0200, Thomas Schmitt wrote:
> Hi,
>
> John Roman wrote:
> > As I understand, a Protective MBR may be located at LBA 0
>
> In the case of the isohybrid partition layout of Matthew J. Garrett,
> which is used by Debian for i386 and amd64, the MBR is not protective.
>
> A bit confusing can be the GPT partition table debris that follows the MBR.
> It is supposed to be ignored by any entity which cares about GPT specs.
> Matthew presented his layout at
> http://mjg59.dreamwidth.org/11285.html
> He talks of Fedora ISOs. Debian joined that layout, but without HFS+
> filesystem.
>
>
> > is this what the live image does
>
> From the view of EFI and many partition editors, Debian's ISO MBR
> effectively marks only one partition, the EFI partition, as entry number 2.
>
> Entry number 1 has type 0x00 to avoid rejection by EFI due to partition 2
> sitting inside partition 1. UEFI 2.4, 5.2.1 specifies:
> "A Partition Record that contains an OSType value of zero or a SizeInLBA
> value of zero may be ignored."
> Partition 1 exists to mark the size of the ISO 9660 filesystem. It is not
> supposed to matter during booting. (BIOS boots by the MBR x86 machine code.)
>
>
> > my desktop (2012) does not seem to understand 0xEF...I wish I knew why.
>
> If you have access to a running Debian System, then you could build a
> grub-mkrescue ISO, which will have a protective MBR and valid GPT.
> If it boots to a GRUB prompt, then we know that your machine would work
> with GPT.
>
> Try to create it with these commands ("minimal/file" is just to have a
> directory and file, on which grub-mkrescue insists):
>
> sudo apt-get install grub-pc grub-efi-ia32-bin grub-efi-amd64-bin xorriso
> mkdir minimal
> echo hello >minimal/file
> grub-mkrescue -o output.iso minimal
>
> Put output.iso onto an USB stick, as you did with the Debian ISO.
>
> -------
>
> Another test proposal:
>
> Knoppix 8.1 ISOs have a different MBR based partition layout than Fedora,
> Debian, et.al. If Knoppix 8.1 (or newer version) boots, then your
> firmware probably hates that Debian partition 1 encloses partition 2,
> despite its type 0x00.
> (Knoppix 8.0 has a partition layout like Debian, but with appended
> partition 3 of type 0x83. Knoppix 7 has no partition table at all.)
>
>
> Have a nice day :)
>
> Thomas
>
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