From mboxrd@z Thu Jan 1 00:00:00 1970 From: "pelzflorian (Florian Pelz)" Subject: Re: ISO installer image: GPT versus MBR partitions Date: Wed, 17 Apr 2019 10:59:52 +0200 Message-ID: <20190417085952.bpjyeld5sv4com6w@pelzflorian.localdomain> References: <20190416203137.adpte7so3awdq2nx@pelzflorian.localdomain> <5051672361776748566@scdbackup.webframe.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([209.51.188.92]:59137) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGgQD-0001OB-Iq for guix-devel@gnu.org; Wed, 17 Apr 2019 05:00:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hGgQC-000288-94 for guix-devel@gnu.org; Wed, 17 Apr 2019 05:00:01 -0400 Content-Disposition: inline In-Reply-To: <5051672361776748566@scdbackup.webframe.org> 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: Thomas Schmitt Cc: bug-xorriso@gnu.org, guix-devel@gnu.org The Parabola ISO parabola-systemd-cli-i686-netinstall-2018.06.02.iso does not inhibit the boot process but also contains no EFI partition so I cannot boot from it. Debian 9.8.0 works, see the end of this mail. On Tue, Apr 16, 2019 at 11:15:56PM +0200, Thomas Schmitt wrote: > Hi, >=20 > i wrote: > > > A broken backup GPT is not supposed to stop EFI from finding its pa= rtition >=20 > Florian Pelz wrote: > > On the 2011 Macbook I am using, the boot process gets stuck before I > > can select the drive to boot from, as long as a USB flash drive with > > this GPT error is in a USB port. >=20 > Did you already test whether it works after you treated the stick > with gdisk expert option 'x' 'e' ? >=20 Nope, it does not. > If it really does work, then i am glad to have written "supposed". >=20 > It would then be interesting to see whether this picky machine boots > from a MBR partition table. > 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? > If so, i will use my copy of this ISO to develop a xorriso run on > the mounted ISO which produces a new ISO with MBR-only layout. >=20 >=20 > (next mail from Florian): > > Actually it still gets stuck after I used fdisk to repair the drive=E2= =80=99s > > GPT. I will check again with a Debian ISO tomorrow. >=20 > Did the GPT repair really work ? > I.e. do other partition editors or kernels have no complaints about the > stick any more ? >=20 >=20 I have overwritten the fdisk-corrected one, but the gdisk-corrected flash drive is considered correct by fdisk. > Another try would be to deface the Apple Partition Map. It's a Mac. > So APM and HFS+ might have some impact. But other than expected by > grub-mkrescue. >=20 > With APM the first bytes of the ISO are > 45 52 08 00 eb 02 ff ff > (which is the APM magic number and also x86 code without effect.) >=20 > Without APM they are other intentionally effectless x86 code: > eb 63 90 90 90 90 90 90 >=20 > If you write the latter 8 bytes over the start of your USB stick, then > APM should not be recognizable any more. >=20 > I inserted the gdisk-corrected USB flash drive and did: $ ghex bytes # put in eb 63 90 90 90 90 90 90 $ sudo dd if=3Dbytes of=3D/dev/sdc Passwort:=20 0+1 Datens=C3=A4tze ein 0+1 Datens=C3=A4tze aus 8 bytes copied, 0,030945 s, 0,3 kB/s It still does not work. > > I will check again with a Debian ISO tomorrow. >=20 > Debian installation ISOs have APM but no HFS+. I.e. their APM is quite > useless. These are: "netinst" ISOs, and the ISO sets for CD, DVD, BD, B= DDL. >=20 > Debian 9 Live ISOs have no APM (and no HFS+). > Version 8 has no EFI equipment but only for legacy BIOS. >=20 >=20 > Have a nice day :) >=20 > Thomas >=20 The Debian ISO works fine and is bootable from its EFI partition. gdisk prints: $ gdisk Downloads/debian-live-9.8.0-amd64-xfce.iso GPT fdisk (gdisk) version 1.0.4 Partition table scan: MBR: MBR only BSD: not present APM: not present GPT: present Found valid MBR and GPT. Which do you want to use? 1 - MBR 2 - GPT 3 - Create blank 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. Command (? for help): p Disk Downloads/debian-live-9.8.0-amd64-xfce.iso: 3811392 sectors, 1.8 GiB Sector size (logical): 512 bytes Disk identifier (GUID): C05B92F2-4B16-4592-BA53-A2025E420B60 Partition table holds up to 248 entries Main partition table begins at sector 2 and ends at sector 63 First usable sector is 64, last usable sector is 3811328 Partitions will be aligned on 8-sector boundaries Total free space is 1 sectors (512 bytes) Number Start (sector) End (sector) Size Code Name 2 1432 2263 416.0 KiB 0700 ISOHybrid1 Regards, Florian