From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [62.89.141.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FAF334DB56; Mon, 15 Jun 2026 17:04:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.89.141.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781543087; cv=none; b=Ymi+PTGKMzWF8JcTVF73EXAhbBWkyV676XQLbOinj95wiD3KXcnzHBSYzJQ9YI1CNsQmf+IMQeTd44SNvPWBs/kRlkKUZdVvrG3ze1Da5CgAsp0d+wiRbF5cqUK8nE3NBk1gPtc5MCRhjSXVgiBRFMn7efV9r/hxOt6iDe3Icpg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781543087; c=relaxed/simple; bh=k9wzEDrn8OWY0tjJOa6e5RtLbGoq+IyJnXkfwU07P80=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QF6uQEQEHg9futom0hrFQOs9iAFBd2WEcfKDttCLlCD6R0Y/uNsPWnjE6MHD5X8PasxdiQqHa54gITg+3IHa1VtAZ+aNpnwCBPcZv1C4K5OpK+yDoWu2/F++GoHEZ6jDbfrui1TsI8VJq+htd6F1Ds5re9OTUVUXD4hh3rbekcI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk; spf=none smtp.mailfrom=ftp.linux.org.uk; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b=SLabnQnx; arc=none smtp.client-ip=62.89.141.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ftp.linux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="SLabnQnx" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description; bh=be/KypQX5Q9fujajARM6Q7r9w26ilWIZmzbrtGfAKys=; b=SLabnQnxi8RKG6kB4YLIrRrIte +jYEaBgX5DOoDOdPOU6k6ypOK6lDxxOMXQzKEUszFj5yTLPDASBaagrmnsOk8tUGdmzHw2XGk68HM 2J1tv7+pE0CjbBOIjeYCz0TsyHOIrqFb8Mb1LadfEs+3t0bUVsavfv//KIZ2S3hmTXIBIqEbnE3qn zsd3Hxu29/Ylu8C3lRKI+WwMxWxUWcLIz0u0fTGyYSKAR/XPPXo0Rkv03xUIJElu5cOtap9hCSZj1 74eb7LaTsGudBKuTsb4/IH254uFPRDECMTh8XzLqKRh9ykQzpGUZV9OECxDmxcCHO22vobRU+rK1T RNRNGWLQ==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.99.2 #2 (Red Hat Linux)) id 1wZAjg-00000000Vxn-0xg6; Mon, 15 Jun 2026 17:04:32 +0000 Date: Mon, 15 Jun 2026 18:04:32 +0100 From: Al Viro To: Vincent Mailhol Cc: Jens Axboe , Davidlohr Bueso , Christian Brauner , Jan Kara , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-efi@vger.kernel.org, linux-fsdevel@vger.kernel.org, Richard Henderson , Matt Turner , Magnus Lindholm , linux-alpha@vger.kernel.org, Vineet Gupta , linux-snps-arc@lists.infradead.org, Russell King , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Huacai Chen , WANG Xuerui , loongarch@lists.linux.dev, Thomas Bogendoerfer , linux-mips@vger.kernel.org, "James E.J. Bottomley" , Helge Deller , linux-parisc@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , linux-s390@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Jonathan Corbet , Shuah Khan , linux-doc@vger.kernel.org Subject: Re: [PATCH 00/19] init: discoverable root partitions, a.k.a. an omittable "root=" cmdline option Message-ID: <20260615170432.GW2636677@ZenIV> References: <20260615-discoverable-root_partitions-v1-0-39c78fac42e2@kernel.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260615-discoverable-root_partitions-v1-0-39c78fac42e2@kernel.org> Sender: Al Viro On Mon, Jun 15, 2026 at 06:08:56PM +0200, Vincent Mailhol wrote: > Tested with GRUB, which implements the LoaderDevicePartUUID EFI variable > in its bli module [3]. With this, I was able to boot a kernel with a > completely empty cmdline and no initrd. > > [1] The Discoverable Partitions Specification (DPS) > Link: https://uapi-group.org/specifications/specs/discoverable_partitions_specification/ > > [2] systemd-gpt-auto-generator > Link: https://www.freedesktop.org/software/systemd/man/latest/systemd-gpt-auto-generator.html > > [3] GRUB -- §16.2 bli > Link: https://www.gnu.org/software/grub/manual/grub/html_node/bli_005fmodule.html So what does that thing, tied to EFI as it is, have to do with architectures where * firmware is rather unlike EFI * firmware wouldn't know what to do with GPT * GRUB is *not* ported to, let alone used such as, say it, the very first one mentioned at your [1]? Or is that conditional upon "if anyone wants to design replacement firmware for those, and if they agree to follow our wishlist"?