On Wed, Sep 11, 2024 at 1:36 PM Lucas De Marchi <lucas.demarchi@xxxxxxxxx> 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" <lucas.demarchi@xxxxxxxxx> > >>>Send time:Tuesday, 09/10/2024 22:00:29 > >>>To: "Masahiro Yamada" <masahiroy@xxxxxxxxxx> > >>>Cc: 3090101217@xxxxxxxxxx, "Michal Marek" <michal.lkml@xxxxxxxxxxx>, "Nick > >>> Desaulniers" <ndesaulniers@xxxxxxxxxx>, "Linux Kbuild mailing list" <linux-kbuild@xxxxxxxxxxxxxxx>, "Linux Kernel Mailing List" <linux-kernel@xxxxxxxxxxxxxxx>, "Jing Leng" <jleng@xxxxxxxxxxxxx> > >>>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@xxxxxxxxxx> wrote: > >>>>> > >>>>> From: Jing Leng <jleng@xxxxxxxxxxxxx> > >>>>> > >>>>> 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 <jleng@xxxxxxxxxxxxx> > >>>>> --- > >>>>> 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@xxxxxxxxxxxxxx/ > Lucas De Marchi > > > > >Thanks > >Lucas De Marchi > > > >> > >>You also can refer to: > >> https://github.com/lengjingzju/cbuild-ng/blob/main/scripts/core/inc.mod.mk > >>1. The complete command is as follows: > >> make -C <Linux kernel source code directory> O=<Linux kernel compilation output directory> src=<Current driver module source code directory> M=<Current driver module compilation output directory> > >>2. If the <Linux kernel source code directory> and the <Linux kernel compilation output directory> are the same, <O=xxx> can be omitted: > >> make -C <Linux kernel source code directory> src=<Current driver module source code directory> M=<Current driver module compilation output directory> > >>2. If the <Current driver module source code directory> and the <Current driver module compilation output directory> are the same, <src=xxx> can be omitted: > >> make -C <Linux kernel source code directory> O=<Linux kernel compilation output directory> M=<Current driver module source code directory> > >> > >>Best Regards! > >>Jing Leng -- Best Regards Masahiro Yamada
