The tools version of fixdep has broken dependencies. It doesn't get
rebuilt if the host compiler or headers change.
Build fixdep with the tools kbuild infrastructure, so fixdep runs on
itself. Due to the recursive dependency, its dependency file is
incomplete the very first time it gets built. In that case build it a
second time to achieve fixdep inception.
Reported-by: Arthur Marsh <arthur.marsh@internode.on.net>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
The 'fixdep' tool is used to post-process dependency files for various
reasons, and it runs after every object file generation command. This
even includes 'fixdep' itself.
In Kbuild, this isn't actually a problem, because it uses a single
command to generate fixdep (a compile-and-link command on fixdep.c), and
afterward runs the fixdep command on the accompanying .fixdep.cmd file.
In tools/ builds (which notably is maintained separately from Kbuild),
fixdep is generated in several phases:
1. fixdep.c -> fixdep-in.o
2. fixdep-in.o -> fixdep
Thus, fixdep is not available in the post-processing for step 1, and
instead, we generate .cmd files that look like:
## from tools/objtool/libsubcmd/.fixdep.o.cmd
# cannot find fixdep (/path/to/linux/tools/objtool/libsubcmd//fixdep)
[...]
These invalid .cmd files are benign in some respects, but cause problems
in others (such as the linked reports).
Because the tools/ build system is rather complicated in its own right
(and pointedly different than Kbuild), I choose to simply open-code the
rule for building fixdep, and avoid the recursive-make indirection that
produces the problem in the first place.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/all/Zk-C5Eg84yt6_nml@google.com/
Link: https://lore.kernel.org/r/20240715203325.3832977-3-briannorris@chromium.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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.
As previously mentioned the fixdep tool is taken from kbuild. It's not
complete backport, only the part that alters the standard dependency
info was taken, the part that adds the CONFIG_* dependency logic will be
probably taken later on.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Kai Germaschewski <kai.germaschewski@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1443004442-32660-4-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
