From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Thomas Schmitt" Subject: Re: ISO installer image: GPT versus MBR partitions Date: Wed, 24 Apr 2019 08:56:57 +0200 Message-ID: <9716677716869443995@scdbackup.webframe.org> References: <20190423214340.tfck3m4gaxtnweog@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]:39757) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hJBnm-00071z-0X for guix-devel@gnu.org; Wed, 24 Apr 2019 02:54:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hJBni-0007Ac-SM for guix-devel@gnu.org; Wed, 24 Apr 2019 02:54:41 -0400 In-Reply-To: <20190423214340.tfck3m4gaxtnweog@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, i wrote: > > > > So programs like /sbin/isosize can tell the image size > > (The [Debian] layout with nested partitions obsoletes the cleanliness > > considerations about partition start at LBA 0.) Florian Pelz wrote > So=E2=80=A6 GPT is wrong for some optical media too? Not in this aspect. GPT partitions must not start at block 0. So the overall ISO superblock is not mountable as partition and thus free to claim the full image size as filesystem size. The problem of restriction to partition size arises with MBR and start block 0 of partition 1, when the nested partition mess of "isohybrid -u" is untangled. > By the way, someone I know has a most peculiar machine called Lenovo > Ideapad 100S which does not boot Guix, but apparently is very picky in > general (cf. ). > Its CPU is claimed to support 64-bit, but its boot firmware rejects > most 64-bit isos. If Guix does not show up in the boot manager, try a plain grub-mkrescue image that was made when GRUB was configured for both EFI variations: 32 bit x86 and 64 x86. My experiments are made when it is configured for those two plus PC-BIOS. The EFI partition then has bootx64.efi and bootia32.efi in /efi/boot/. > It might just not be feasible to please every EFI system. Let's see how far we get. This research not only helps Guix but also GRUB. (And it has a tendency to reveal my bugs in xorriso.) Have a nice day :) Thomas