From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.domeneshop.no (smtp.domeneshop.no [194.63.252.55]) (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 7A8A7175B1; Sat, 14 Sep 2024 07:19:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.63.252.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726298407; cv=none; b=FyRydCC/0CusFnj29TJyrWBSk2tXwHiBgSViLnMCEridAPnewdngSAsNWMaM43QCUrrwSBq1YG6nvDyxHRfNncE/3MYfXShFp146m9AJV3DIqm4br7T4tfn/wC60pkecclHDQfs6T8bEBcGnKwbxw0FoIp1UzqpVBPLUZsuQhYI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726298407; c=relaxed/simple; bh=+nCRBcECe+f7eLWxihkl9KlyRYWxmo7Kggbc1KNnjQc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Wmq1mVQ6hF2PGd/mWOjM3t7sLGiK2CULPiE+i9/B5GxSBljseY/SHCip+mh2hqS9vVAxkVJ8bpDh8PoqFBAdPN419IaJY7e950TQ3eskEfYvR9zLwxjWf2RbUByjXyfXaCHHyQkYxYkrB1MpmRVbE3O+SdhdUx8rq9L5YWqsEn4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=fjasle.eu; spf=pass smtp.mailfrom=fjasle.eu; dkim=pass (2048-bit key) header.d=fjasle.eu header.i=@fjasle.eu header.b=T5XcjebT; arc=none smtp.client-ip=194.63.252.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=fjasle.eu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fjasle.eu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fjasle.eu header.i=@fjasle.eu header.b="T5XcjebT" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fjasle.eu; s=ds202307; h=In-Reply-To:Content-Transfer-Encoding:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ZNbttXLmsVTMJFfGZ6eGNTGy2rEvBvnnhCiM1YadOGs=; b=T5XcjebTzldcSw0eTGWOH00qZf 1/tC4KrHsifNzy9aqGeOfujkr5GUa/C3rWvyB7zeO8Fj91XU8P5z6bF5KsmE6MCeqPjc+X1eS+fBj 7mvMnXJWOmncZNBgX89XsijRX0aSNPvoyQ3LexQlx68rDu3v0if8yeDeLK/sZzSgH2L9j4q5Z33Ru 7ndW+bJcrhu1AU4HJYmCivVwzzzaMzD7FmRfFM6rHYTyXogkWGxf4xBPx/+CBlq8sFYDOhkkSBSWg sqgaSg2ER2LF36QtyqCkruf3/DPbOUBLwgT2puhhqJjOk33xos+r7QII+06b2lqDHb5xFwC+GOPtZ yyhIwB+w==; Received: from [2001:9e8:9c6:1501:3235:adff:fed0:37e6] (port=46920 helo=lindesnes.fjasle.eu) by smtp.domeneshop.no with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1spN4T-0088YS-FG; Sat, 14 Sep 2024 09:19:53 +0200 Date: Sat, 14 Sep 2024 09:19:42 +0200 From: Nicolas Schier To: Lucas De Marchi Cc: Masahiro Yamada , Jing Leng <3090101217@zju.edu.cn>, Michal Marek , Nick Desaulniers , Linux Kbuild mailing list , Linux Kernel Mailing List , Jing Leng Subject: Re: External modules with O=... (was: Re: [PATCH] kbuild: Fix include path in scripts/Makefile.modpost) Message-ID: <20240914-loutish-crouching-echidna-3bfd6d@lindesnes> References: <442e8058.43a4.191dea175d7.Coremail.3090101217@zju.edu.cn> Precedence: bulk X-Mailing-List: linux-kernel@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: On Wed, Sep 11, 2024 at 10:38:58AM -0500, Lucas De Marchi wrote: > On Wed, Sep 11, 2024 at 04:28:30PM GMT, Masahiro Yamada wrote: > > On Wed, Sep 11, 2024 at 1:36 PM Lucas De Marchi > > wrote: > > > > > > On Tue, Sep 10, 2024 at 09:43:14PM GMT, Lucas De Marchi wrote: > > > >On Wed, Sep 11, 2024 at 09:10:09AM GMT, Jing Leng wrote: > > > >>>-----Original Messages----- > > > >>>From: "Lucas De Marchi" > > > >>>Send time:Tuesday, 09/10/2024 22:00:29 > > > >>>To: "Masahiro Yamada" > > > >>>Cc: 3090101217@zju.edu.cn, "Michal Marek" , "Nick > > > >>> Desaulniers" , "Linux Kbuild mailing list" , "Linux Kernel Mailing List" , "Jing Leng" > > > >>>Subject: External modules with O=... (was: Re: [PATCH] kbuild: Fix include path in scripts/Makefile.modpost) > > > >>> > > > >>>Hi, I was pointed to this thread since I'm trying something similar > > > >>>in kmod's testsuite. See below. > > > >>> > > > >>>On Tue, May 24, 2022 at 02:52:45AM GMT, Masahiro Yamada wrote: > > > >>>>On Tue, May 17, 2022 at 7:51 PM <3090101217@zju.edu.cn> wrote: > > > >>>>> > > > >>>>> From: Jing Leng > > > >>>>> > > > >>>>> When building an external module, if users don't need to separate the > > > >>>>> compilation output and source code, they run the following command: > > > >>>>> "make -C $(LINUX_SRC_DIR) M=$(PWD)". At this point, "$(KBUILD_EXTMOD)" > > > >>>>> and "$(src)" are the same. > > > >>>>> > > > >>>>> If they need to separate them, they run "make -C $(KERNEL_SRC_DIR) > > > >>>>> O=$(KERNEL_OUT_DIR) M=$(OUT_DIR) src=$(PWD)". Before running the > > > >>>>> command, they need to copy "Kbuild" or "Makefile" to "$(OUT_DIR)" to > > > >>>>> prevent compilation failure. > > > >>>>> > > > >>>>> So the kernel should change the included path to avoid the copy operation. > > > >>>>> > > > >>>>> Signed-off-by: Jing Leng > > > >>>>> --- > > > >>>>> scripts/Makefile.modpost | 3 +-- > > > >>>>> 1 file changed, 1 insertion(+), 2 deletions(-) > > > >>>>> > > > >>>>> diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost > > > >>>>> index 48585c4d04ad..0273bf7375e2 100644 > > > >>>>> --- a/scripts/Makefile.modpost > > > >>>>> +++ b/scripts/Makefile.modpost > > > >>>>> @@ -87,8 +87,7 @@ obj := $(KBUILD_EXTMOD) > > > >>>>> src := $(obj) > > > >>>>> > > > >>>>> # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS > > > >>>>> -include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \ > > > >>>>> - $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile) > > > >>>>> +include $(if $(wildcard $(src)/Kbuild), $(src)/Kbuild, $(src)/Makefile) > > > >>>>> > > > >>>>> # modpost option for external modules > > > >>>>> MODPOST += -e > > > >>>>> -- > > > >>>>> 2.17.1 > > > >>>>> > > > >>>> > > > >>>> > > > >>>>I do not think "M=$(OUT_DIR) src=$(PWD)" is the official way, > > > >>>>but this patch is a clean up. > > > >>> > > > >>>I tried what is in this patch and also tried to find an official way in > > > >>>the docs. > > > > > > There is no official way. > > > > > >>> > > > >>>In kmod's testsuite we build dummy kernel modules to exercise the API. > > > >>>https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/testsuite/module-playground > > > >>> > > > >>>This works: > > > >>> make -C /lib/modules/$(uname -r)/build M=$PWD > > > >>> > > > >>>This doesn't: > > > >>> make -C /lib/modules/$(uname -r)/build M=$PWD O=/tmp/kmod_test_modules > > > > > > > > O= points the output directory of the kernel, > > not the output directory of the external modules. > > > > > > /lib/modules/$(uname -r)/build > > is the clean source tree. > > > > /tmp/kmod_test_modules > > contains the build artifacts of vmlinux and > > in-tree modules. > > > > Then, the command you gave would work. > > > > > > > > > > > > > > > >>> > > > >>>I also tried the variants above with setting src, but all of them give > > > >>>me errors - I used 6.10 and 6.11-rc7 for these tests. > > > >>> > > > >>>Is there a way to do this? > > > >>> > > > >>>thanks > > > >>>Lucas De Marchi > > > >>> > > > >>>> > > > >>>>Applied to linux-kbuild. Thanks. > > > >>>> > > > >>>> > > > >>>>-- > > > >>>>Best Regards > > > >>>>Masahiro Yamada > > > >> > > > >>Hi Masahiro, > > > > > > > >I guess you meant Lucas :) > > > > > > > >> > > > >>I think your intention is to separate the source code from the compiled output. > > > >>The correct command should be: > > > >> make -C /lib/modules/$(uname -r)/build src=$PWD M=/tmp/kmod_test_modules > > > > > > > >oh, looks like this works. Apparently my mistake was trying to set O= > > > >like I normally do for in-tree modules. > > > > > > spoke too early... It worked because I was in another machine pointing > > > to a 6.8 kernel. It seems like something broke between 6.9 and 6.10. > > > > > > Running a quick bisect, it's pointing to this commit: > > > 9a0ebe5011f4 ("kbuild: use $(obj)/ instead of $(src)/ for common pattern rules") > > > > > > Overriding 'src' from the command is not allowed. That's why. > > > > > > > Error like below: > > > > > > $ make -j$(nproc) -C ~/p/linux-dim/src MddPWD/build srcx=$PWD > > > make: Entering directory '/home/ldmartin/p/linux-dim/src' > > > make[2]: *** No rule to make target '/home/ldmartin/p/kmod/testsuite/module-playground/build/mod-simple.o', needed by '/home/ldmartin/p/kmod/testsuite/module-playground/build/'. Stop. > > > make[1]: *** [/home/ldmartin/p/linux-dim/src/Makefile:1922: /home/ldmartin/p/kmod/testsuite/module-playground/build] Error 2 > > > make: *** [Makefile:240: __sub-make] Error 2 > > > make: Leaving directory '/home/ldmartin/p/linux-dim/src' > > > > > > I suggested M=relative-path + VPATH= > > but I do not know what you want to achieve. > > > > https://lore.kernel.org/linux-kbuild/CAK7LNATGGibmjZzYX_A2SkJthmOPbKw2K3R7JYuHTWzgGL2Zjg@mail.gmail.com/ > > but that is only for in-tree modules, not external modules, right? > Quick reproducer on what I expected would work: > > git clone https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git > cd kmod/testsuite/module-playground > make -C $KDIR M=$PWD O=$PWD/build > > So... did I get the below statement right? > > There never was an official way to build external modules with > source and build in different directories. Up until 6.9 we > could pass `-C M= src=` > for unofficial way. After that there's no alternative. yes, AFAICT your summary describes the situation quite precisely. Kind regards, Nicolas