From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Wed, 03 Sep 2025 08:53:16 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uthMr-007YZQ-1O for lore@lore.pengutronix.de; Wed, 03 Sep 2025 08:53:16 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1uthMq-0005KT-6L for lore@pengutronix.de; Wed, 03 Sep 2025 08:53:16 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version: Content-Transfer-Encoding:Content-Type:References:In-Reply-To:Date:Cc:To:From :Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qwGGqAINbCh8pt+fXysXQK8iM7rf1mWv1/9kBvPRG70=; b=BZHETy8+H2/IUy5G9Qg5APeat+ lU0rlSaA9D/cdJrUnD3p2qEYFoPyJUdQX5IUfJ8GjFl6Ia/7AeKS4t68CxAkUlgoiJ4FAtvBO4Ht1 ocdmb1OxbqSaHCBzHKPEHObkG5MnHH8TOU4QVv0j7uXNMvMv28TIxsiHYzirlW+uAi9fBrGwZFb16 T3A7t1OQfgxinIip5zYEHO0vdZkB+XGJ4mI8J3Z8u/+iXJXcc63YlnhldpSROUE26EzniZNw4r54x AVtwlC6mmgjzTrSrZPM4pF2w9b7RODuirL26f1V2EtWKg5QQvOjz8rdcuRQUNUA8Z5rYhATF3k+0q G7AFf0Lg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uthMK-00000004oLf-1H39; Wed, 03 Sep 2025 06:52:44 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uthJl-00000004nE5-10o6 for barebox@lists.infradead.org; Wed, 03 Sep 2025 06:50:06 +0000 Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1uthJj-0004h8-Cn; Wed, 03 Sep 2025 08:50:03 +0200 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77]) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1uthJi-003W5w-39; Wed, 03 Sep 2025 08:50:02 +0200 Received: from localhost ([127.0.0.1] helo=[IPv6:::1]) by ptz.office.stw.pengutronix.de with esmtp (Exim 4.96) (envelope-from ) id 1uthJi-009u9H-2Y; Wed, 03 Sep 2025 08:50:02 +0200 Message-ID: <234808b66fb792f4b9ab50654dd3c018e90db6b8.camel@pengutronix.de> From: Jan =?ISO-8859-1?Q?L=FCbbe?= To: Tobias Waldekranz , Ahmad Fatoum , barebox@lists.infradead.org Cc: Richard Weinberger , Michael Olbrich , anis chali , Marco Felsch Date: Wed, 03 Sep 2025 08:50:02 +0200 In-Reply-To: <874itk4jzn.fsf@waldekranz.com> References: <20250828150637.2222474-1-tobias@waldekranz.com> <07a7e6e0-f0dd-4969-888a-b616fe337158@pengutronix.de> <87frd83p9h.fsf@waldekranz.com> <24ac7ede-0f36-4283-b654-9cccdfa97a37@pengutronix.de> <28a00db6c1bdf69f93e6ef7210e11c5dfa368411.camel@pengutronix.de> <874itk4jzn.fsf@waldekranz.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.46.4-2 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250902_235005_285725_66994155 X-CRM114-Status: GOOD ( 30.46 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.8 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 0/5] dm: Initial work on a device mapper X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) On Tue, 2025-09-02 at 23:34 +0200, Tobias Waldekranz wrote: > On tis, sep 02, 2025 at 16:46, Jan L=C3=BCbbe wrote: > > On Tue, 2025-09-02 at 11:03 +0200, Ahmad Fatoum wrote: > > > > Yeah I noticed that, _very_ useful. For Infix, if we end up going w= ith > > > > LVM, I suspect we won't be able to send all of that info along with= the > > > > commandline, and will end up needing to figure that out (again) in = an > > > > initramfs - but for most cases I think it would work really well! > > >=20 > > > Ah, didn't think of LVM. If mix-and-match is no problem for you, then > > > doing it in the initramfs is a workable solution of course. > >=20 > > If you are thinking about LVM, you may want to take a look at how Andro= id is > > using dm-linear for "dynamic partitions": > > https://source.android.com/docs/core/ota/dynamic_partitions/ab_launch > > https://source.android.com/docs/core/ota/dynamic_partitions/implement > >=20 > > This is also related to virtual A/B: > > https://source.android.com/docs/core/ota/virtual_ab > >=20 > > The components are "snapuserd" and "dm-user" (which was not merged): > > https://lpc.events/event/11/contributions/1049/attachments/826/1562/202= 1%20LPC_%20dm-snapshot%20in%20user%20space.pdf > > https://lwn.net/Articles/838986/ > >=20 > > I'm not sure what they use at the moment... >=20 > Very interesting, thank you! >=20 > I get why they want something like that for Android, but it does feel > quite daunting to deploy for the systems I typically work on. >=20 > If one was to ignore the business of background-merging of COW data > etc. and was just looking to have a way of allocating volumes from > persistent storage, do you see any advantages with Android's metadata > format and/or tooling over that provided by the LVM2 project? LVM2 in general is quite complex. Some people don't like that it's not easi= ly possible to know (in udev/systemd) when all volumes are found and set-up, m= aking boot time dependencies difficult. The Android metadata (or something simila= r) seems to be simple enough to implement in a bootloader. So, as we only need= a small subset of the full LVM functionality on embedded devices, perhaps the= re's space for a lightweight alternative? :) Jan --=20 Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |