linux-kernel - Re: [PATCH v2] kbuild: remove trailing slashes from $(KBUILD

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Date:   Thu, 17 Jun 2021 10:37:09 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Johannes Berg <johannes@...solutions.net>,
        Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH v2] kbuild: remove trailing slashes from $(KBUILD_EXTMOD)

On Wed, Jun 2, 2021 at 11:02 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> M= (or KBUILD_EXTMOD) generally expects a directory path without any
> trailing slashes, like M=a/b/c.
>
> If you add a trailing slash, like M=a/b/c/, you will get ugly build
> logs (two slashes in a series), but it still works fine as long as it
> is consistent between 'make modules' and 'make modules_install'.
>
> The following commands correctly build and install the modules.
>
>   $ make M=a/b/c/ modules
>   $ sudo make M=a/b/c/ modules_install
>
> Since commit ccae4cfa7bfb ("kbuild: refactor scripts/Makefile.modinst"),
> a problem happens if you add a trailing slash only for modules_install.
>
>   $ make M=a/b/c modules
>   $ sudo make M=a/b/c/ modules_install
>
> No module is installed in this case, Johannes Berg reported. [1]
>
> Trim any trailing slashes from $(KBUILD_EXTMOD).
>
> I used the 'dirname' command to remove all the trailing slashes in
> case someone adds more slashes like M=a/b/c/////. The Make's built-in
> function, $(dir ...) cannot take care of such a case.
>
> [1]: https://lore.kernel.org/lkml/10cc8522b27a051e6a9c3e158a4c4b6414fd04a0.camel@sipsolutions.net/
>
> Fixes: ccae4cfa7bfb ("kbuild: refactor scripts/Makefile.modinst")
> Reported-by: Johannes Berg <johannes@...solutions.net>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---

Applied to linux-kbuild.



> Changes in v2:
>   - Use $(filter %/, ) so that the shell invocation is avoided
>     if M= is already good.
>
>  Makefile | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index b79e0e8acbe3..8018b8adbcaf 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -129,6 +129,11 @@ endif
>  $(if $(word 2, $(KBUILD_EXTMOD)), \
>         $(error building multiple external modules is not supported))
>
> +# Remove trailing slashes
> +ifneq ($(filter %/, $(KBUILD_EXTMOD)),)
> +KBUILD_EXTMOD := $(shell dirname $(KBUILD_EXTMOD).)
> +endif
> +
>  export KBUILD_EXTMOD
>
>  # Kbuild will save output files in the current working directory.
> --
> 2.27.0
>


-- 
Best Regards
Masahiro Yamada