From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="S/HaNrIl" Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49C18128 for ; Thu, 7 Dec 2023 06:27:28 -0800 (PST) Received: by mail-pj1-x102e.google.com with SMTP id 98e67ed59e1d1-28670a7ba84so819185a91.2 for ; Thu, 07 Dec 2023 06:27:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1701959248; x=1702564048; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=FnUqi8dAEgGMyEzBxdD28hEtaCGQO1gXXHV0T1kN7CU=; b=S/HaNrIlZ1DvlTNB0E5lv/B/jagUzSzYVkBFDPkoNIN1LiRa1I0xHQINUKVCg0TNSR SM8n1x6D6WJHzB+l3IkgyqBLYA5Jz9TniilXPvrPTiF/RF22DXM2XhS7PgktPvNbpLWh eQy/d/QFNFVcy+m/YZA/NdrB5w7zq9ehc4c6U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701959248; x=1702564048; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=FnUqi8dAEgGMyEzBxdD28hEtaCGQO1gXXHV0T1kN7CU=; b=ukc8+WiqRdhotABhbbCGQ2uEtM/HJrzVOfj/aI+hKp7IfK3sITiUCwf6EzE38t/km7 Ku1rZBaNg+djxxG4QVEvH502WS6cHid7MISQkcIVX1JVfoE3uW7QZyvhJmW72QgpSVwq s6pDtMY2ETHD1r+c7Egvu+i6/seJ2a/w0RqQ97ux8UzBFAS1pAx4PByDVRGast2nOjZt SIyKOTJOi6DcVKzBiGEk3Me+AKQ/NI7igVaDr0sezQJ3DbdWX9hB093hs4uQazFtKSOi kxO+Wvu4NMTab+8WFFoAlfNDD0Q7qyEINGybFN4fI1xXoFsgD2HtrR6YIC4SOETk4Dxh JP/Q== X-Gm-Message-State: AOJu0YzcWw51XBbCWhZpWM8sSG6mVdGcURmk6oPznnX/ei13tTmEu6Hn V9YqWOEEU9FySWM1Z7jHbIhRYQ== X-Google-Smtp-Source: AGHT+IH8AzbuT3bEW5QtQ3VpbuixskHTKbrXXL1zs3HHhHdzRy4lAaYreOoFMvEXA8A9ADp82mykHw== X-Received: by 2002:a17:90a:e009:b0:286:6cc0:b918 with SMTP id u9-20020a17090ae00900b002866cc0b918mr2087016pjy.79.1701959247711; Thu, 07 Dec 2023 06:27:27 -0800 (PST) Received: from google.com ([2401:fa00:1:10:e0f4:e383:e626:f567]) by smtp.gmail.com with ESMTPSA id d15-20020a170902654f00b001cfc2d024edsm1507200pln.29.2023.12.07.06.27.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Dec 2023 06:27:27 -0800 (PST) Date: Thu, 7 Dec 2023 22:27:23 +0800 From: Chen-Yu Tsai To: Laurent Pinchart Cc: Simon Glass , linux-arm-kernel@lists.infradead.org, Masahiro Yamada , Ahmad Fatoum , U-Boot Mailing List , Nicolas Schier , Tom Rini , Catalin Marinas , Jonathan Corbet , Nathan Chancellor , Nick Terrell , Will Deacon , linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, workflows@vger.kernel.org Subject: Re: [PATCH v9 2/2] arm64: boot: Support Flat Image Tree Message-ID: <20231207142723.GA3187877@google.com> References: <20231202035511.487946-1-sjg@chromium.org> <20231202035511.487946-3-sjg@chromium.org> <20231203153401.GV8402@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-doc@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: <20231203153401.GV8402@pendragon.ideasonboard.com> On Sun, Dec 03, 2023 at 05:34:01PM +0200, Laurent Pinchart wrote: > Hi Simon, > > Thank you for the patch. > > On Fri, Dec 01, 2023 at 08:54:42PM -0700, Simon Glass wrote: > > Add a script which produces a Flat Image Tree (FIT), a single file > > containing the built kernel and associated devicetree files. > > Compression defaults to gzip which gives a good balance of size and > > performance. > > > > The files compress from about 86MB to 24MB using this approach. > > > > The FIT can be used by bootloaders which support it, such as U-Boot > > and Linuxboot. It permits automatic selection of the correct > > devicetree, matching the compatible string of the running board with > > the closest compatible string in the FIT. There is no need for > > filenames or other workarounds. > > > > Add a 'make image.fit' build target for arm64, as well. Use > > FIT_COMPRESSION to select a different algorithm. > > > > The FIT can be examined using 'dumpimage -l'. > > > > This features requires pylibfdt (use 'pip install libfdt'). It also > > requires compression utilities for the algorithm being used. Supported > > compression options are the same as the Image.xxx files. For now there > > is no way to change the compression other than by editing the rule for > > $(obj)/image.fit > > > > While FIT supports a ramdisk / initrd, no attempt is made to support > > this here, since it must be built separately from the Linux build. > > FIT images are very useful, so I think this is a very welcome addition > to the kernel build system. It can get tricky though: given the > versatile nature of FIT images, there can't be any > one-size-fits-them-all solution to build them, and striking the right > balance between what makes sense for the kernel and the features that > users may request will probably lead to bikeshedding. As we all love > bikeshedding, I thought I would start selfishly, with a personal use > case :-) This isn't a yak-shaving request though, I don't see any reason > to delay merging this series. > > Have you envisioned building FIT images with a subset of DTBs, or adding > DTBOs ? Both would be fairly trivial extensions to this script by > extending the supported command line arguments. It would perhaps be more > difficult to integrate in the kernel build system though. This leads me > to a second question: would you consider merging extensions to this > script if they are not used by the kernel build system, but meant for > users who manually invoke the script ? More generally, is the script We'd also be interested in some customization, though in a different way. We imagine having a rule file that says X compatible string should map to A base DTB, plus B and C DTBO for the configuration section. The base DTB would carry all common elements of some device, while the DTBOs carry all the possible second source components, like different display panels or MIPI cameras for instance. This could drastically reduce the size of FIT images in ChromeOS by deduplicating all the common stuff. > meant to be used stand-alone as well, in which case its command line > arguments need to remain backward-compatible, or do you see it as being > internal to the kernel ? [...] ChenYu