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Re: Automatically installing GRUB on multiple drives

From Nicolas George <george@nsup.org>
Newsgroups linux.debian.user
Subject Re: Automatically installing GRUB on multiple drives
Date 2024-01-26 10:30 +0100
Message-ID <I0qH8-5FF0-3@gated-at.bofh.it> (permalink)
References <HZRJn-5kko-19@gated-at.bofh.it> <HZSvL-5kAn-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Thomas Schmitt (12024-01-24):
> The Debian installation and live ISOs have MBR partitions with only a
> flimsy echo of GPT. There is a GPT header block and an entries array.
> But it does not get announced by a Protective MBR. Rather they have two
> partitions of which one is meant to be invisible to EFI ("Empty") and
> one is advertised as EFI partition:
> 
> $ /sbin/fdisk -l debian-12.2.0-amd64-netinst.iso
> ...
> Disklabel type: dos
> ...
> Device                           Boot Start     End Sectors  Size Id Type
> debian-12.2.0-amd64-netinst.iso1 *        0 1286143 1286144  628M  0 Empty
> debian-12.2.0-amd64-netinst.iso2       4476   23451   18976  9.3M ef EFI (FAT-12
> 
> So any system which boots this ISO from USB stick does not rely on
> the presence of a valid GPT.

You seem to be assuming that the system will first check sector 0 to
parse the MBR and then, if the MBR declares a GPT sector try to use the
GPT.

I think it is the other way around on modern systems: it will first
check sector 1 for a GPT header, and only if it fails check sector 0. Or
not check sector 0 at all if legacy mode has been removed.

> This layout was invented by Matthew J. Garrett for Fedora and is still
> the most bootable of all possible weird ways to present boot stuff for
> legacy BIOS and EFI on USB stick in the same image.

I think I invented independently something similar.

https://nsup.org/~george/comp/live_iso_usb/grub_hybrid.html

Regards,

-- 
  Nicolas George

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Thread

Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-24 11:20 +0100
  Re: Automatically installing GRUB on multiple drives "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-24 12:50 +0100
    Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-24 21:10 +0100
      Re: Automatically installing GRUB on multiple drives "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-24 22:00 +0100
        Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-26 10:30 +0100
          Re: Automatically installing GRUB on multiple drives "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-26 11:10 +0100
      Re: Automatically installing GRUB on multiple drives Tim Woodall <debianuser@woodall.me.uk> - 2024-01-26 04:40 +0100
        Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-26 08:50 +0100
          Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-26 09:40 +0100
            Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-26 10:20 +0100
              Re: Automatically installing GRUB on multiple drives "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-26 10:50 +0100
              Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-26 11:00 +0100
              Re: Automatically installing GRUB on multiple drives Tim Woodall <debianuser@woodall.me.uk> - 2024-01-26 14:20 +0100
                Re: Automatically installing GRUB on multiple drives Tim Woodall <debianuser@woodall.me.uk> - 2024-01-26 14:30 +0100
                Re: Automatically installing GRUB on multiple drives gene heskett <gheskett@shentel.net> - 2024-01-26 14:50 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-26 15:40 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-26 15:20 +0100
      Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-26 17:00 +0100
        Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-26 17:00 +0100
          Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-28 17:20 +0100
            Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-28 17:50 +0100
              Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-28 21:10 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-28 23:00 +0100
            Re: Automatically installing GRUB on multiple drives Dan Ritter <dsr@randomstring.org> - 2024-01-28 18:20 +0100
              Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-28 18:40 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-28 21:10 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-28 23:00 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-29 17:30 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-30 01:00 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-30 22:00 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-31 16:20 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-31 23:00 +0100
                Re: Automatically installing GRUB on multiple drives Franco Martelli <martellif67@gmail.com> - 2024-02-02 14:50 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-02-02 20:00 +0100
                Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-02-03 19:30 +0100
            Re: Automatically installing GRUB on multiple drives Franco Martelli <martellif67@gmail.com> - 2024-01-29 14:50 +0100
              Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-29 18:00 +0100
                Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-29 18:10 +0100
                Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-30 21:40 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-31 23:30 +0100
                Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-31 23:30 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-02-02 04:50 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-30 21:40 +0100
                Re: Automatically installing GRUB on multiple drives <tomas@tuxteam.de> - 2024-01-29 18:50 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-30 21:50 +0100
                Re: Automatically installing GRUB on multiple drives <tomas@tuxteam.de> - 2024-01-31 06:40 +0100
                Re: Automatically installing GRUB on multiple drives hw <hw@adminart.net> - 2024-01-31 23:50 +0100
                Re: Automatically installing GRUB on multiple drives Max Nikulin <manikulin@gmail.com> - 2024-02-02 03:50 +0100
        Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-26 17:00 +0100
  Re: Automatically installing GRUB on multiple drives Charles Curley <charlescurley@charlescurley.com> - 2024-01-24 15:30 +0100
    Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-24 15:50 +0100
      Re: Automatically installing GRUB on multiple drives Felix Miata <mrmazda@earthlink.net> - 2024-01-24 17:10 +0100
        Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-24 21:00 +0100
          Re: Automatically installing GRUB on multiple drives Felix Miata <mrmazda@earthlink.net> - 2024-01-25 00:10 +0100
  Re: Automatically installing GRUB on multiple drives Franco Martelli <martellif67@gmail.com> - 2024-01-24 17:40 +0100
    Re: Automatically installing GRUB on multiple drives Nicolas George <george@nsup.org> - 2024-01-24 21:00 +0100
  Re: Automatically installing GRUB on multiple drives Andy Smith <andy@strugglers.net> - 2024-01-24 21:30 +0100

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