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