[PATCH 0/7] tools build: Fix header removal build issue

[Jiri Olsa <jolsa@kernel.org>]

hi,
for dependency tracking we currently use targets that fall out
of the gcc -MD command. We store this info in the .cmd file and
include as makefile during the build.

This format put object as target and all the c and header files
as dependencies, like:

  util/abspath.o: util/abspath.c /usr/include/stdc-predef.h util/cache.h \
   /usr/include/bits/wordsize.h /usr/include/gnu/stubs.h \
   ...

If any of those dependency header files (krava.h below) is removed
the build fails on:

  make[1]: *** No rule to make target 'krava.h', needed by 'inc.o'.  Stop.

This patch adds fixdep helper, that is used by kbuild
to alter the shape of the object dependencies like:

  source_util/abspath.o := util/abspath.c

  deps_util/abspath.o := \
    /usr/include/stdc-predef.h \
    util/cache.h \
    ...

  util/abspath.o: $(deps_util/abspath.o)

  $(deps_util/abspath.o):

With this format the header removal won't make the build fail, because
it'll be picked up by the last empty target defined for each header.


thanks,
jirka


Cc: Kai Germaschewski <kai.germaschewski@gmx.de>
---
Jiri Olsa (7):
      tools build: Add Makefile.include
      tools build: Add test for missing include
      tools build: Add fixdep dependency helper
      tools build: Move dependency copy into function
      tools build: Make fixdep helper part of the build process
      perf tools: Rename single_dep target to prepare
      tools build: Build fixdep helper from perf and basic libs

 tools/build/Build                   |   1 +
 tools/build/Build.include           |  17 +++++++++---
 tools/build/Documentation/Build.txt |  52 +++++++++++++++++++++++++++---------
 tools/build/Makefile                |  43 ++++++++++++++++++++++++++++++
 tools/build/Makefile.build          |   7 +++++
 tools/build/Makefile.include        |   6 +++++
 tools/build/fixdep.c                | 168 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tools/build/tests/ex/Build          |   1 +
 tools/build/tests/ex/Makefile       |  13 +++++----
 tools/build/tests/ex/ex.c           |   2 ++
 tools/build/tests/ex/inc.c          |   8 ++++++
 tools/build/tests/run.sh            |  27 +++++++++++++++++++
 tools/lib/api/Makefile              |   6 +++--
 tools/lib/bpf/Makefile              |   6 +++--
 tools/lib/lockdep/Makefile          |   6 +++--
 tools/perf/Makefile.perf            |  32 +++++++++++-----------
 16 files changed, 352 insertions(+), 43 deletions(-)
 create mode 100644 tools/build/Build
 create mode 100644 tools/build/Makefile
 create mode 100644 tools/build/Makefile.include
 create mode 100644 tools/build/fixdep.c
 create mode 100644 tools/build/tests/ex/inc.c