From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E227424337A; Sun, 9 Feb 2025 20:42:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739133725; cv=none; b=aMnsXNpVqckJKBrdNO+AGjM/RRuRv/LzgElHuA+5kI/LmsMfvL2S6yH+n4dno0EtRbL3j6DfZIE+l/RneaBWAm9GuVmYfXZY/n5AA0E3mE5/Q0vpG/Kqt0t8TfndsHLUoiyofAwpHN9x8q4U7wQ9yc4u5yZX2k5Z0ZrcxClMqRg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739133725; c=relaxed/simple; bh=I5K6zxbY/URQKv0ExjhoGFG70Vc1gvwB7vWXZFIu2Cc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lg73IWXpd0guRluw9Usf1g6B7RWUvxy3m6bNUnjElPbgTmaJnKMjHP83G2sywnhL7zkRn4mLurpuyE/1gHALeCwP6DkC2sLMUfgsMHFgerby9sGcJ147vLj/hom/wFmpejn71p+7T8zPg5HsXBelOIEnpOWn5VYrVWxjwiC4mbs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mvb6ZNQq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mvb6ZNQq" 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> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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.