releases/4.19.34/kbuild-invoke-syncconfig-if-include-config-auto.conf.patch

   1 From c3d2bf390f739423a7022f93b3b30c3d3e9f6308 Mon Sep 17 00:00:00 2001
   2 From: Masahiro Yamada <yamada.masahiro@socionext.com>
   3 Date: Fri, 22 Feb 2019 16:40:10 +0900
   4 Subject: kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
   5
   6 [ Upstream commit 9390dff66a52d1a60c6e517d8fa6cdbdffc83cb1 ]
   7
   8 If include/config/auto.conf.cmd is lost for some reasons, it is not
   9 self-healing, so the top Makefile misses to run syncconfig.
  10 Move include/config/auto.conf.cmd to the target side.
  11
  12 I used a pattern rule instead of a normal rule here although it is
  13 a bit gross.
  14
  15 If the rule were written with a normal rule like this,
  16
  17   include/config/auto.conf \
  18   include/config/auto.conf.cmd \
  19   include/config/tristate.conf: $(KCONFIG_CONFIG)
  20           $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
  21
  22 ... syncconfig would be executed per target.
  23
  24 Using a pattern rule makes sure that syncconfig is executed just once
  25 because Make assumes the recipe will create all of the targets.
  26
  27 Here is a quote from the GNU Make manual [1]:
  28
  29 "Pattern rules may have more than one target. Unlike normal rules,
  30 this does not act as many different rules with the same prerequisites
  31 and recipe. If a pattern rule has multiple targets, make knows that
  32 the rule's recipe is responsible for making all of the targets. The
  33 recipe is executed only once to make all the targets. When searching
  34 for a pattern rule to match a target, the target patterns of a rule
  35 other than the one that matches the target in need of a rule are
  36 incidental: make worries only about giving a recipe and prerequisites
  37 to the file presently in question. However, when this file's recipe is
  38 run, the other targets are marked as having been updated themselves."
  39
  40 [1]: https://www.gnu.org/software/make/manual/html_node/Pattern-Intro.html
  41
  42 Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
  43 Signed-off-by: Sasha Levin <sashal@kernel.org>
  44 ---
  45  Makefile | 7 +++++--
  46  1 file changed, 5 insertions(+), 2 deletions(-)
  47
  48 diff --git a/Makefile b/Makefile
  49 index 8de5fab711d8..f1a5d7deaf5f 100644
  50 --- a/Makefile
  51 +++ b/Makefile
  52 @@ -626,12 +626,15 @@ ifeq ($(may-sync-config),1)
  53  -include include/config/auto.conf.cmd
  54
  55  # To avoid any implicit rule to kick in, define an empty command
  56 -$(KCONFIG_CONFIG) include/config/auto.conf.cmd: ;
  57 +$(KCONFIG_CONFIG): ;
  58
  59  # The actual configuration files used during the build are stored in
  60  # include/generated/ and include/config/. Update them if .config is newer than
  61  # include/config/auto.conf (which mirrors .config).
  62 -include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
  63 +#
  64 +# This exploits the 'multi-target pattern rule' trick.
  65 +# The syncconfig should be executed only once to make all the targets.
  66 +%/auto.conf %/auto.conf.cmd %/tristate.conf: $(KCONFIG_CONFIG)
  67         $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig
  68  else
  69  # External modules and some install targets need include/generated/autoconf.h
  70 --
  71 2.19.1
  72