From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Thomas Schmitt" Subject: Re: ISO installer image: GPT versus MBR partitions Date: Wed, 17 Apr 2019 12:23:56 +0200 Message-ID: <63026723884801035449@scdbackup.webframe.org> References: <20190417085952.bpjyeld5sv4com6w@pelzflorian.localdomain> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([209.51.188.92]:46947) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGhhS-0006RX-JT for guix-devel@gnu.org; Wed, 17 Apr 2019 06:21:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hGhhR-0003Rw-Kb for guix-devel@gnu.org; Wed, 17 Apr 2019 06:21:54 -0400 In-Reply-To: <20190417085952.bpjyeld5sv4com6w@pelzflorian.localdomain> List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: bug-xorriso@gnu.org Cc: guix-devel@gnu.org Hi, Florian Pelz wrote: > $ gdisk Downloads/debian-live-9.8.0-amd64-xfce.iso > ... > Found valid MBR and GPT. Which do you want to use? > 1 - MBR > 2 - GPT > ... > Your answer: 2 > Using GPT and creating fresh protective MBR. > Warning! Main partition table overlaps the first partition by 64 blocks! > You will need to delete this partition or resize it in another utility. > ... > Number Start (sector) End (sector) Size Code Name > 2 1432 2263 416.0 KiB 0700 ISOHybrid1 This operation has killed the MBR partition table with the entry for the EFI partition. Due to the odd layout introduced for Fedora ISOs in SYSLINUX program "isohybrid", there is a GPT partition entry which marks the EFI FAT image. But it does not have the EFI type GUID. So EFI won't recognize it. (This layout has been adopted by Debian and others who use ISOLINUX for BIOS and GRUB for EFI. It needs MBR partition type 0x00 for the ISO partition. The GPT ISO partition is madly starting at block 0. Partition editors are entitled to hate it. But well, the user decides what to do. I can only give advise.) There remains the boot path of legacy BIOS via the MBR x86 code. > The Debian ISO works fine and is bootable from its EFI partition. Did you try booting before or after the gdisk run ? > > Is guixsd-install-0.15.0.i686-linux.iso > > suitable for that machine (modulo GPT backup position) ? > Without changing the ISO=E2=80=99s partition tables, it does not work. > What should I change? I will develop and test a xorriso repack run for the mounted ISO which produces MBR partitioning without GPT and APM. Maybe this evening. Have a nice day :) Thomas