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 X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFD76C433E0 for ; Tue, 26 Jan 2021 17:27:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C6F382075F for ; Tue, 26 Jan 2021 17:27:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726009AbhAZR1A (ORCPT ); Tue, 26 Jan 2021 12:27:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389555AbhAZHV6 (ORCPT ); Tue, 26 Jan 2021 02:21:58 -0500 X-Greylist: delayed 73382 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 25 Jan 2021 23:21:12 PST Received: from antares.kleine-koenig.org (antares.kleine-koenig.org [IPv6:2a01:4f8:c0c:3a97::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55F52C061573; Mon, 25 Jan 2021 23:21:12 -0800 (PST) Received: from antares.kleine-koenig.org (localhost [127.0.0.1]) by antares.kleine-koenig.org (Postfix) with ESMTP id 46AFDADE69D; Tue, 26 Jan 2021 08:21:09 +0100 (CET) Received: from antares.kleine-koenig.org ([94.130.110.236]) by antares.kleine-koenig.org (antares.kleine-koenig.org [94.130.110.236]) (amavisd-new, port 10024) with ESMTP id V7DnAz6ZVq0I; Tue, 26 Jan 2021 08:21:07 +0100 (CET) Received: from taurus.defre.kleine-koenig.org (unknown [IPv6:2a02:8071:b5ad:20fc:e287:a8e4:9290:29e6]) by antares.kleine-koenig.org (Postfix) with ESMTPSA; Tue, 26 Jan 2021 08:21:07 +0100 (CET) To: Masahiro Yamada Cc: Michal Marek , Linux Kbuild mailing list , Linux Kernel Mailing List , linux-arm-kernel , cyril@debamax.com, Arnd Bergmann , Maxime Ripard , DTML , Geert Uytterhoeven , Rob Herring References: <20210125105757.661240-1-uwe@kleine-koenig.org> From: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= Subject: Re: [PATCH] cmd_dtc: Enable generation of device tree symbols Message-ID: <9d9bb0f6-d4f4-b1b9-a4c4-786987578085@kleine-koenig.org> Date: Tue, 26 Jan 2021 08:20:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Md9uBspQZ8si26wbTEXGrXNDQsO6WS1FX" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --Md9uBspQZ8si26wbTEXGrXNDQsO6WS1FX Content-Type: multipart/mixed; boundary="bIO7wac1lK89xpNlKc4oBcYpFRZsCPvJE"; protected-headers="v1" From: =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= To: Masahiro Yamada Cc: Michal Marek , Linux Kbuild mailing list , Linux Kernel Mailing List , linux-arm-kernel , cyril@debamax.com, Arnd Bergmann , Maxime Ripard , DTML , Geert Uytterhoeven , Rob Herring Message-ID: <9d9bb0f6-d4f4-b1b9-a4c4-786987578085@kleine-koenig.org> Subject: Re: [PATCH] cmd_dtc: Enable generation of device tree symbols References: <20210125105757.661240-1-uwe@kleine-koenig.org> In-Reply-To: --bIO7wac1lK89xpNlKc4oBcYpFRZsCPvJE Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hello Masahiro, On 1/25/21 10:53 PM, Masahiro Yamada wrote: > On Mon, Jan 25, 2021 at 8:07 PM Uwe Kleine-K=C3=B6nig wrote: >> >> Adding the -@ switch to dtc results in the binary devicetrees containi= ng >> a list of symbolic references and their paths. This is necessary to >> apply device tree overlays e.g. on Raspberry Pi as described on >> https://www.raspberrypi.org/documentation/configuration/device-tree.md= =2E >> >> Obviously the downside of this change is an increas of the size of the= >> generated dtbs, for an arm out-of-tree build (multi_v7_defconfig): >> >> $ du -s arch/arm/boot/dts* >> 101380 arch/arm/boot/dts-pre >> 114308 arch/arm/boot/dts-post >> >> so this is in average an increase of 12.8% in size. >> >> Signed-off-by: Uwe Kleine-K=C3=B6nig >=20 >=20 > (CCing DT ML.) makes sense, thanks. > https://www.spinics.net/lists/linux-kbuild/msg27904.html >=20 > See Rob's comment: >=20 > "We've already rejected doing that. Turning on '-@' can grow the dtb > size by a significant amount which could be problematic for some > boards." The patch was created after some conversation on irc which continued after I sent the patch. I added the participating parties to Cc:. The (relevant) followups were: Geert suggested to always generate the symbols and provide a way to strip the symbols for installation if and when they are not needed. Rob said: "I'm less concerned with the size increases, but rather that labels go from purely source syntax to an ABI. I'd rather see some decision as to which labels are enabled or not." And then I learned with hints from Rob and Geert that symbols are not really necessary for overlays, you just cannot use named labels. But using target-path =3D "/soc/i2c@23473245"; or target =3D <&{/soc/i2c@23473245}>; instead of target =3D <&i2c1>; works fine. (And if you need to add a phandle the &{/path/to/node} construct should work, too (but I didn't test).) Using labels is a tad=20 nicer, but the problem I wanted to address with my patch now has a known = different solution. Best regards Uwe --bIO7wac1lK89xpNlKc4oBcYpFRZsCPvJE-- --Md9uBspQZ8si26wbTEXGrXNDQsO6WS1FX Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAmAPwtwACgkQwfwUeK3K 7AlKXwgAm+kcs8YKGPW7BkNgCAJ44hDVJaUMseUumkbzSu+J7mJb/cEZ0bG87K+J SzhQcJQ2LoASq0ZMg6dTn2PyqBDv63nnKmHiFVa+3z9J9EWPK+ZvZSyvoX0PLjiO /IoBG+Vaei0hav2poeDjBdSWybhP567KYiYPkrmlbUyt9Aq6fgaEqgOGnnaZbxII YOJ51Aec1JjAzlb8uD9dOYPmNKAFqlfONfBcr9abIACfc6FEKQytp/yvn6UvkHrL tdP1lubPpzJXFJp8Md4yCPRRUbTpB8b7qvLXIge0YVUeU641roNdDnX9TY818ffA qXrWfwyBKeMboKt30RTEfkHmEmIDew== =nA4F -----END PGP SIGNATURE----- --Md9uBspQZ8si26wbTEXGrXNDQsO6WS1FX--