From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx08-00178001.pphosted.com ([91.207.212.93]:26656 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728512AbgAQPLu (ORCPT ); Fri, 17 Jan 2020 10:11:50 -0500 Subject: Re: [RFC PATCH 1/3] dtc: Add dtb build information option References: <20200113181625.3130-1-alexandre.torgue@st.com> <20200113181625.3130-2-alexandre.torgue@st.com> <20200116005741.GB54439@umbus> <20200117090937.GU54439@umbus> From: Alexandre Torgue Message-ID: Date: Fri, 17 Jan 2020 16:11:19 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Rob Herring , David Gibson Cc: Frank Rowand , Masahiro Yamada , Michal Marek , Simon Glass , devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux Kbuild mailing list , Devicetree Compiler , Steve McIntyre David, Rob, On 1/17/20 3:43 PM, Rob Herring wrote: > On Fri, Jan 17, 2020 at 6:26 AM David Gibson > wrote: >> >> On Thu, Jan 16, 2020 at 09:58:23AM +0100, Alexandre Torgue wrote: >>> Hi David >>> >>> On 1/16/20 1:57 AM, David Gibson wrote: >>>> On Mon, Jan 13, 2020 at 07:16:23PM +0100, Alexandre Torgue wrote: >>>>> This commit adds the possibility to add build information for a DTB. >>>>> Build information can be: build date, DTS version, "who built the DTB" >>>>> (same kind of information that we get in Linux with the Linux banner). >>>>> >>>>> To do this, an extra option "-B" using an information file as argument >>>>> has been added. If this option is used, input device tree is appended with >>>>> a new string property "Build-info". This property is built with information >>>>> found in information file given as argument. This file has to be generated >>>>> by user and shouldn't exceed 256 bytes. >>>>> >>>>> Signed-off-by: Alexandre Torgue >>>> >>>> At the very least, this patch of the series will need to be sent to >>>> upstream dtc first. >>> >>> Ok sorry. I thought that sending all the series would give more >>> information. >> >> That's fair enough, but in order to merge, you'll need to post against >> upstream dtc. ok >> >>>> I'm also not terribly clear on what you're trying to accomplish here, >>>> and why it's useful. >>> >>> Let's take Kernel boot at example (but could be extend to other DTB "users" >>> like U-Boot). When Linux kernel booting we get a log that gives useful >>> information about kernel image: source version, build date, people who built >>> the kernel image, compiler version. This information is useful for debug and >>> support. The aim is to get same kind of information but for the DTB. >>> >>>> Since you're doing this specifically for use with dtbs built in the >>>> kernel build, could you just use a: >>>> Build-info = /incbin/ "build-info.txt"; >>>> in each of the in-kernel .dts files? >>> >>> My first idea was to not modify all existing .dts files. Adding an extra >>> option in dtc is (for me) the softer way to do it. I mean, compile >>> information should come through compiler without modify .dts files outside >>> from dtc. In this way it will be easy to everybody using dtc (inside our >>> outside Linux tree) to add dtb build info (even if they don't how to write a >>> dts file). >> >> But you're not really having this information coming from the >> compiler. Instead you're adding a compiler option that just force >> includes another file into the generated tree, and it's up to your >> build scripts to put something useful into that file. >> >> I don't really see that as preferable to modifying the .dts files. I agree. I took example on kernel version info. It doesn't come from gcc but from auto-generated file. I thought it was the easier way to process. But I understand your concerns. As it is not generated by dtc itself, dtc should not be modified. >> >> I also dislike the fact that the option as proposed is much more >> general than the name suggests, but also very similar too, but much >> more specific than the existing /incbin/ option. >> >> What might be better would be to have a dtc option which force appends >> an extra .dts to the mail .dts compiled. You can then put an overlay >> template in that file, something like: >> >> &{/} { >> linux,build-info = /incbin/ "build-info.txt; >> } > > I like this suggestion either as an include another dts file or an > overlay. The latter could be useful as a way to maintain current dtb > files while splitting the source files into base and overlay dts > files. First suggestion will imply to modify an huge part of dts file (not a big modification but a lot :)). Second one (dtbo) sounds good. In this case this dtso will be created from build-info.txt and applied when dtb is built. So no impacts on current dts file. I'm right ? Alex > > But no, let's not prepend this with 'linux'. It's not a property > specific for Linux to consume. > > Rob >