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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Thu, 14 Mar 2019 02:44:55 +0900
Message-ID: <CAK7LNATeqmC3daAxTk9J0r0YHB425gTFYLave2aMth6rmejREQ@mail.gmail.com>
Subject: Re: [PATCH v2] kbuild: add workaround for Debian make-kpkg
To:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Cc:     Ben Hutchings <ben@decadent.org.uk>,
        Riku Voipio <riku.voipio@linaro.org>,
        Manoj Srivastava <srivasta@debian.org>,
        Liz Zhang <lizzha@microsoft.com>,
        Lili Deng <v-lide@microsoft.com>,
        Manoj Srivastava <manoj.srivastava.1962@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Mar 8, 2019 at 6:15 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> Since commit 3812b8c5c5d5 ("kbuild: make -r/-R effective in top
> Makefile for old Make versions"), make-kpkg is not working.
>
> make-kpkg directly includes the top Makefile of Linux kernel, and
> appends some debian_* targets.
>
>   /usr/share/kernel-package/ruleset/kernel_version.mk:
>
>     # Include the kernel makefile
>     override dot-config := 1
>     include Makefile
>     dot-config := 1
>
> I did not know the kernel Makefile was used in that way, and it is
> hard to guarantee the behavior when the kernel Makefile is included
> by another Makefile from a different project.
>
> It looks like Debian Stretch stopped providing make-kpkg. Maybe it is
> obsolete and being replaced with 'make deb-pkg' etc. but still widely
> used.
>
> This commit adds a workaround; if the top Makefile is included by
> another Makefile, skip sub-make in order to make the main part visible.
> 'MAKEFLAGS += -rR' does not become effective for GNU Make < 4.0, but
> Debian/Ubuntu is already using newer versions.
>
> The effect of this commit:
>
>   Debian 8 (Jessie)  : Fixed
>   Debian 9 (Stretch) : make-kpkg (kernel-package) is not provided
>   Ubuntu 14.04 LTS   : NOT Fixed
>   Ubuntu 16.04 LTS   : Fixed
>   Ubuntu 18.04 LTS   : Fixed
>
> This commit cannot fix Ubuntu 14.04 because it installs GNU Make 3.81,
> but its support will end in Apr 2019, which is before the Linux v5.1
> release.
>
> I added warning so that nobody would try to include the top Makefile.
>
> Fixes: 3812b8c5c5d5 ("kbuild: make -r/-R effective in top Makefile for old Make versions")
> Reported-by: Liz Zhang <lizzha@microsoft.com>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Tested-by: Lili Deng <v-lide@microsoft.com>
> Cc: Manoj Srivastava <srivasta@debian.org>
> ---

Applied to linux-kbuild.


> Changes in v2:
>   - Drop the unimportant comment about PowerPC
>
>  Makefile | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 4fb8896..6039685 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -31,6 +31,16 @@ _all:
>  # descending is started. They are now explicitly listed as the
>  # prepare rule.
>
> +# Ugly workaround for Debian make-kpkg:
> +# make-kpkg directly includes the top Makefile of Linux kernel. In such a case,
> +# skip sub-make to support debian_* targets in ruleset/kernel_version.mk, but
> +# displays warning to discourage such abusage.
> +ifneq ($(word 2, $(MAKEFILE_LIST)),)
> +$(warning Do not include top Makefile of Linux Kernel)
> +sub-make-done := 1
> +MAKEFLAGS += -rR
> +endif
> +
>  ifneq ($(sub-make-done),1)
>
>  # Do not use make's built-in rules and variables
> --
> 2.7.4
>


-- 
Best Regards
Masahiro Yamada