From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 62267C0219D for ; Sun, 9 Feb 2025 20:43:42 +0000 (UTC) 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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=PegLxjr7RGLlGHR54YwuPBdBXg3Ixf5ePUyHS8FCXNs=; b=IsaWkbbuttKi/soQ7xHHkZTG5U OxYp34c/ILh6om7d4mUZle+CtMWHpQb0g+HNu5I4gpnXf+AzyH+TUFfrTW3+S6eMB0x440vNoaoZo sii270EqxYtw4QJP4pmbSzw0a9kEH7lohKGfKEtbZF0HCIb+Q5pg2Cc3JFcjnbSo0VpO5pN74Z7gm Z1ps2nniu9/DLaMvr0VS+L5K2SkkPnT7VSLUXDjLEG7+y1RqBYdscloAadw7+W3gw6w6Ir3feUFZp BYGSMK0I0DDojvNYMAEUBjA0voL4TuIxfRNZ2GDvBFsZEU3mh036hgQpz6dwfvaUqTXKb9QuUP3ZO XMXOGLlw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1thE9M-0000000FWtP-0yWq; Sun, 09 Feb 2025 20:43:32 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1thE7x-0000000FWb8-2KmE; Sun, 09 Feb 2025 20:42:06 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 0323C5C4A66; Sun, 9 Feb 2025 20:41:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB0C8C4CEDD; Sun, 9 Feb 2025 20:41:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1739133724; bh=I5K6zxbY/URQKv0ExjhoGFG70Vc1gvwB7vWXZFIu2Cc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Mvb6ZNQqXlj09hq+unmSZoCfmod0TI+N53mH8hNPSmhVyaECG7qL/VeLfhSozBwyK bKp+3joGTS/8s3clIpcXU+Kf3coxgVOphSyzF4hIIfi6JPcitd2fnaTr4OYmTK+2eo HlHqV/qAg7XSOsMq2x0B+/PJIDWofzpZ5yMR8hNDTGhHx/Y9oX1jWuLDZoWAREW4+R DJBNXzGWKtGcx9XY6KOHAp5SdQBSySW6jRv0MlYbzTruhoFWCjOEJhK0IaUSIjok8i Gx7waD6FniX2f5APSdEPIG+AUN5MSH7PclqCC2YAZNH9a44UXgOHUXHV2I40nrNzbv P8DS5GHanX+6A== Date: Sun, 9 Feb 2025 22:41:46 +0200 From: Mike Rapoport To: Krzysztof Kozlowski Cc: linux-kernel@vger.kernel.org, Alexander Graf , Andrew Morton , Andy Lutomirski , Anthony Yznaga , Arnd Bergmann , Ashish Kalra , Benjamin Herrenschmidt , Borislav Petkov , Catalin Marinas , Dave Hansen , David Woodhouse , Eric Biederman , Ingo Molnar , James Gowans , Jonathan Corbet , Mark Rutland , Paolo Bonzini , Pasha Tatashin , "H. Peter Anvin" , Peter Zijlstra , Pratyush Yadav , Rob Herring , Rob Herring , Saravana Kannan , Stanislav Kinsburskii , Steven Rostedt , Thomas Gleixner , Tom Lendacky , Usama Arif , Will Deacon , devicetree@vger.kernel.org, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH v4 14/14] Documentation: KHO: Add memblock bindings Message-ID: References: <20250206132754.2596694-1-rppt@kernel.org> <20250206132754.2596694-15-rppt@kernel.org> <45df0d7a-622a-4268-9683-c5c6067483c3@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250209_124205_678733_229C835A X-CRM114-Status: GOOD ( 27.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Feb 09, 2025 at 04:23:09PM +0100, Krzysztof Kozlowski wrote: > On 09/02/2025 16:10, Mike Rapoport wrote: > > On Sun, Feb 09, 2025 at 11:29:41AM +0100, Krzysztof Kozlowski wrote: > >> On 06/02/2025 14:27, Mike Rapoport wrote: > >>> From: "Mike Rapoport (Microsoft)" > >>> > >>> We introduced KHO into Linux: A framework that allows Linux to pass > >>> metadata and memory across kexec from Linux to Linux. KHO reuses fdt > >>> as file format and shares a lot of the same properties of firmware-to- > >>> Linux boot formats: It needs a stable, documented ABI that allows for > >>> forward and backward compatibility as well as versioning. > >> > >> Please use subject prefixes matching the subsystem. You can get them for > >> example with `git log --oneline -- DIRECTORY_OR_FILE` on the directory > >> your patch is touching. For bindings, the preferred subjects are > >> explained here: > >> https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters > > > > These are not devicetree binding for communicating data from firmware to > > the kernel. These bindings are specific to KHO which is perfectly > > reflected by the subject. > > No, it is not. None of the bindings use above subject prefix. > > > > > Just a brief reminder from v2 discussion: > > (https://lore.kernel.org/linux-mm/20231222193607.15474-1-graf@amazon.com/) > > > > "For quick reference: KHO is a new mechanism this patch set introduces > > which allows Linux to pass arbitrary memory and metadata between kernels > > on kexec. I'm reusing FDTs to implement the hand over protocol, as > > Linux-to-Linux boot communication holds very similar properties to > > firmware-to-Linux boot communication. So this binding is not about > > hardware; it's about preserving Linux subsystem state across kexec. > > does not matter. You added file to ABI documentation so you must follow > that ABI documentation rules. One rule is proper subject prefix. No, it does not. It's a different ABI. FDT is a _data structure_ that provides cross platform unified, versioned, introspectable data format. Documentation/devicetree/bindings standardizes it's use for describing hardware, but KHO uses FDT _data structure_ to describe state of the kernel components that will be reused by the kexec'ed kernel. KHO is a different namespace from Open Firmware Device Tree, with different requirements and different stakeholders. Putting descriptions of KHO data formats in Documentation/kho rather than in Documentation/devicetree/bindings was not done to evade review of Open Firmware Device Tree maintainers, but rather to emphasize that KHO FDT _is not_ Open Firmware Device Tree. > Best regards, > Krzysztof -- Sincerely yours, Mike.