From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id CA443158089 for ; Wed, 18 Oct 2023 21:07:29 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 66E3C2BC110; Wed, 18 Oct 2023 21:07:24 +0000 (UTC) Received: from ciao.gmane.io (ciao.gmane.io [116.202.254.214]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 2A9272BC018 for ; Wed, 18 Oct 2023 21:07:24 +0000 (UTC) Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1qtDlD-0003Xo-14 for gentoo-user@lists.gentoo.org; Wed, 18 Oct 2023 23:07:23 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: gentoo-user@lists.gentoo.org From: Grant Edwards Subject: [gentoo-user] Re: OFF TOPIC Need Ubuntu network help Date: Wed, 18 Oct 2023 21:07:15 -0000 (UTC) Message-ID: References: <17dbcf2a-13c7-b8c0-69f1-a09e5288cfd5@gmail.com> <2581583.Lt9SDvczpP@rogueboard> <2647385.k3LOHGUjKi@rogueboard> User-Agent: slrn/1.0.3 (Linux) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply X-Archives-Salt: 12f86308-f974-4208-91c9-7ce424d92143 X-Archives-Hash: 3685ae27f7318e505399f97a84826812 On 2023-10-18, Michael wrote: > >> The protective MBR and the BIOS boot partition are two different, >> unrelated things. The BIOS boot partition is a real partition (usually >> 1-2MB in size) that's present in the GPT parition table. It's used by >> Grub as a place to store its files. > > Yes, this is needed on GPT disks when installed on BIOS MoBos. There is a way to install Grub on GPT disks without it, but it takes extra work and isn't worth it. You have to lock certain files in place under /boot/grub so that block-lists can be embedded in sector 0. All of the disk label utilities I've seen recently will, by default, leave a sizable empty space between the primary GPT table and the start of the first partition (which typically starts at a 1MB offset from the start of the disk). I've never understood why Grub won't use that space they way it will use the empty space between an MBR and the first partition. >> It must be the first partition, and it doesn't have a real >> filesystem (grub uses some sort of private filesystem): > > I'm not sure it uses any filesystem. I understood it uses a raw sector jump > from the MBR to the GPT partition type 0xEE. I've read a couple vague but differing descriptions of it. One description specifically referred to "files" (plural) and some sort of grub-private-internal filesystem. However, it could be that it's nothing but a single "file" starting at block 0 in that partition. Whatever it is, it seems to be "opaque" in that Grub puts stuff in that partition, Grub later uses that stuff, and nobody else needs to know or care what it is or how it's organized. I haven't looked through the Grub source code to try to see inside the black box... -- Grant