> -----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=$(PWD)" is the official way, > >but this patch is a clean up. > > I tried what is in this patch and also tried to find an official way in > the docs. > > In kmod's testsuite we build dummy kernel modules to exercise the API. > https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/testsuite/module-playground > > This works: > make -C /lib/modules/$(uname -r)/build M=$PWD > > This doesn't: > make -C /lib/modules/$(uname -r)/build M=$PWD O=/tmp/kmod_test_modules > > I also tried the variants above with setting src, but all of them give > me errors - I used 6.10 and 6.11-rc7 for these tests. > > Is there a way to do this? > > thanks > Lucas De Marchi > > > > >Applied to linux-kbuild. Thanks. > > > > > >-- > >Best Regards > >Masahiro Yamada Hi Masahiro, I think your intention is to separate the source code from the compiled output. The correct command should be: make -C /lib/modules/$(uname -r)/build src=$PWD M=/tmp/kmod_test_modules 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
