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 C252D39525A; Wed, 4 Feb 2026 08:46:23 +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=1770194783; cv=none; b=RWE/Cv97hSWoKREnD5R91kl2x7K5tehkh6R1vQxNdEf+8yEGgjg0uSOXHhUHAQx7LppdRpd9kuVYB73txRgZiVaSyqhXh8pK8MBNkdQDr28sRlu5fV+VYmcESr+cqeU1mSAbPQhcsauymAUBmKNKIaJeMrxvMXPubJNXTrgrC+8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770194783; c=relaxed/simple; bh=gmNMCCI5NZOsnSxNVmd/K1kyzXPGn2eU/LmGenWiOGc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=OR5ipXP/M72eCrIx0DmBviosotzSRxnaGomGMySxaQUdMhIJShSGeZ8U3QCTQXsz7JfvaCF75JPioyitRRUIxdaJODWupk2+V8PkPmwVQdCz59NMxbM01/PgYoyYtWCinXfCCt8ZO2HgdDNVK5GiQv7QsBf8bUcegfnxYgehZ8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fDeJ+4Wj; 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="fDeJ+4Wj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3EF5C16AAE; Wed, 4 Feb 2026 08:46:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770194783; bh=gmNMCCI5NZOsnSxNVmd/K1kyzXPGn2eU/LmGenWiOGc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fDeJ+4Wj2yC+G7JFjFrm9qnaVc17U5liGPQcgKgvVyxnC2eVJYKT0iw1vJQosft8Y OxvJsG9JLhlbOQkZlX6RLlru8JJfdTcXYMrOa0YUT0NA22q/3Dguk+OV3t3cfj2GmO od/e51+k+o4iChCys4sGUQHGW/LCGjL4g+wgCGcn43yCeBe3+6DhYrTsopqtkgqx2L 3DxN4tqyUGBeL3NY2WpWaSzfXz6JpEV1Y8XalvqcAUUvcoThbie7WdqGyvbXq+5E6Z wX4NEC9UUD4XJfkwF/c0moOUWfvCrvnjKEHTK7+/Aj3xhPtxEUW/OkPp39wM1hXF5j 6xCdLeefW55Yw== Date: Wed, 4 Feb 2026 01:46:17 -0700 From: Nathan Chancellor To: Icenowy Zheng Cc: Nicolas Schier , Masahiro Yamada , Abel Vesa , Mingcong Bai , WangYuli , Inochi Amaoto , James Le Cuirot , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, Rong Zhang , Rob Herring , Saravana Kannan , devicetree@vger.kernel.org Subject: Re: [PATCH] kbuild: install-extmod-build: do not exclude scripts/dtc/libfdt/ Message-ID: <20260204084617.GB3900164@ax162> References: <20260201130259.2906768-1-zhengxingda@iscas.ac.cn> <20260204021603.GA2646832@ax162> <20260204084517.GA3900164@ax162> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260204084517.GA3900164@ax162> On Wed, Feb 04, 2026 at 01:45:23AM -0700, Nathan Chancellor wrote: > On Wed, Feb 04, 2026 at 11:27:24AM +0800, Icenowy Zheng wrote: > > 在 2026-02-04星期三的 11:26 +0800，Icenowy Zheng写道： > > > 在 2026-02-03星期二的 19:16 -0700，Nathan Chancellor写道： > > > > + Rob, Saravana, and devicetree@ since this concerns files they > > > > own. > > > > > > > > On Sun, Feb 01, 2026 at 09:02:59PM +0800, Icenowy Zheng wrote: > > > > > There exists a header file in include/linux/ called libfdt.h that > > > > > is > > > > > just a wrapper for libfdt header file in scripts/dtc/libfdt/. > > > > > This > > > > > makes > > > > > the headers inside libfdt copy at scripts/dtc/libfdt/ part of the > > > > > kernel > > > > > headers for building external modules. > > > > > > > > > > Do not exclude them, otherwise modules that include > > > > > > > > > > will fail to build externally. > > > > > > > > > > Fixes: aaed5c7739be ("kbuild: slim down package for building > > > > > external modules") > > > > > Signed-off-by: Icenowy Zheng > > > > > > > > This does indeed bring back scripts/dtc/libfdt back into the > > > > headers > > > > package that I examined. However, how does including libfdt.h in an > > > > external module actually work, even with this change? libfdt > > > > appears > > > > to > > > > be built into vmlinux IIUC and I do not see any EXPORT_SYMBOLs in > > > > the > > > > list, so how can you actually use any of the functions from libfdt > > > > within the module? Would you just build and link the pieces that > > > > your > > > > module needs using the other source files? > > > > > > To be honest what I met is quite weird -- my module [1] does not use > > > libfdt at all. However, as a MIPS platform-specific module, it > > > includes > > > arch/mips/include/asm/bootinfo.h, which pulls in libfdt.h. > > > > > > Or maybe I should prevent libfdt.h inclusion from other kernel > > > headers? > > > It looks like only two headers in MIPS architecture-specific code > > > includes libfdt.h, asm/bootinfo.h and asm/machine.h . > > Ah, thanks for that information. Moving the libfdt.h bits out of > bootinfo.h does not seem like it would be too difficult but I am less > sure about asm/machine.h. Alternatively, maybe this could be avoided by > separating out what you would need from bootinfo.h into its own header > but I did not look too hard. > > As for a solution within install-extmod-build, maybe the libfdt headers > could be included so that inadvertent inclusions of libfdt.h do not > break the build but the link fails if the module actually tries to use > any libfdt functions? > > > Ah, forgot to place the [1] reference link, although I doubt whether > > it's really related to the context: > > > > [1] https://github.com/Icenowy/mips-loong-3nod-laptop-driver > > This was helpful for testing the following diff, so thanks for providing > it still. > > Cheers, > Nathan Of course forgot to provide said diff... diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build index 2576cf7902db..45cc3863e8a7 100755 --- a/scripts/package/install-extmod-build +++ b/scripts/package/install-extmod-build @@ -25,6 +25,9 @@ mkdir -p "${destdir}" find "arch/${SRCARCH}" -name Kbuild.platforms -o -name Platform find include \( -name config -o -name generated \) -prune -o \( -type f -o -type l \) -print find_in_scripts + echo scripts/dtc/libfdt/fdt.h + echo scripts/dtc/libfdt/libfdt.h + echo scripts/dtc/libfdt/libfdt_env.h ) | tar -c -f - -C "${srctree}" -T - | tar -xf - -C "${destdir}" {