Re: [RFC PATCH v2 0/4] Add device tree build information

From: Alexandre Torgue <alexandre.torgue@st.com>
To: Steve McIntyre <steve.mcintyre@linaro.org>
Cc: Frank Rowand <frowand.list@gmail.com>, <robh+dt@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	<david@gibson.dropbear.id.au>, <sjg@chromium.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-kbuild@vger.kernel.org>,
	<devicetree-compiler@vger.kernel.org>,
	Ian Lepore <ian@freebsd.org>
Subject: Re: [RFC PATCH v2 0/4] Add device tree build information
Date: Tue, 31 Mar 2020 17:00:45 +0200	[thread overview]
Message-ID: <afa534b0-c671-600f-f344-de7026dc2c79@st.com> (raw)
In-Reply-To: <20200331010347.GF4037@linaro.org>

Hi Steeve

On 3/31/20 3:03 AM, Steve McIntyre wrote:
> Hi Alexandre,
> 
> On Mon, Mar 02, 2020 at 01:55:55PM +0100, Alexandre Torgue wrote:
>> On 2/28/20 6:47 PM, Frank Rowand wrote:
>>>> This would require modifying every single main .dts file to get the build info
>>>> I would prefer the method that Ian and David came up with (sorry, no lore link,
>>>> it did not go to lkml).  Extract from David's email:
>>>>
>>>>      Date:   Tue, 21 Jan 2020 13:05:25 +1100
>>>>      From:   David Gibson <david@gibson.dropbear.id.au>
>>>>      Subject: Re: [RFC PATCH 1/3] dtc: Add dtb build information option
>>>>
>>>>      > Given that dts files are run through the C preprocessor before being
>>>>      > fed to dtc, the build script could use the '-include' flag to force-
>>>>      > include a fragment containing generated build info without any need to
>>>>      > modify existing dts files.
>>>>
>>>>      Uh... maybe.  -include will essentially prepend the forced file, which
>>>>      is a bit awkward for our purposes.  It means that the prepended file
>>>>      would need the /dts-v1/ tag, and we couldn't have it in the main files
>>>>      which would be a bit confusing.  I think it would also cause problems
>>>>      with any /memreserve/ tags and means that the main tree could in
>>>>      theory overwrite the build information which we don't necessarily
>>>>      want.
>>>>
>>>>      I guess we could build things the other way around: have the main .dts
>>>>      file specified with -include and have the dts on the dtc commandline
>>>>      be a fixed one with the build information.  It'd be a little weird,
>>>>      though.
>>>>
>>>> -Frank
>>
>> Yes. I try briefly this idea but I got issues with dts-v1 tag. I agree, it is
>> cleaner to not modify input dts file. I can rework int this way.
> 
> Have you made any progress on this please?

Unfortunately no. I cook something locally but not yet upstream-able.
Due to project issue I didn't find time to work on it. I think (I hope) 
to be less busy next week and so I'll restart it.

regards
alex

> 
> Cheers,
> 