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* [PATCH] kbuild: add workaround for Debian make-kpkg
@ 2019-03-06 16:00 Masahiro Yamada
  2019-03-06 20:59 ` Ben Hutchings
  2019-03-06 21:01 ` Ben Hutchings
  0 siblings, 2 replies; 8+ messages in thread
From: Masahiro Yamada @ 2019-03-06 16:00 UTC (permalink / raw)
  To: linux-kbuild
  Cc: Liz Zhang, Lili Deng, Ben Hutchings, Riku Voipio,
	Masahiro Yamada, Michal Marek, linux-kernel

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.

Looks like Debian Stretch stopped providing make-kpkg (except PowerPC).
Maybe it is obsolete and being replaced with 'make deb-pkg' etc.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>
---

 Makefile | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Makefile b/Makefile
index ef4b32c..925d870 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


^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2019-03-09 20:32 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-03-06 16:00 [PATCH] kbuild: add workaround for Debian make-kpkg Masahiro Yamada
2019-03-06 20:59 ` Ben Hutchings
2019-03-06 21:01 ` Ben Hutchings
2019-03-07  4:03   ` Masahiro Yamada
2019-03-07  6:36     ` Ben Hutchings
     [not found]       ` <CABkpOEUqJWn62VZoTA5UEnbDieiYR9y3diRQhZuOVe6hOoBNhA@mail.gmail.com>
2019-03-07 21:56         ` Ben Hutchings
2019-03-08  6:42           ` Masahiro Yamada
2019-03-09 20:32             ` Ben Hutchings

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