kbuild: add workaround for Debian make-kpkg
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 Maybe it is
obsolete and being replaced with 'make deb-pkg' etc.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>