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96f30c8f0a
All built targets need fixdep to be built first, before handling object
dependencies [1]. We're missing one such dependency before the libsubcmd
target.
This resolves .cmd file generation issues such that the following
sequence produces many fewer results:
$ git clean -xfd tools/
$ make tools/objtool
$ grep "cannot find fixdep" $(find tools/objtool -name '*.cmd')
In particular, only a buggy tools/objtool/libsubcmd/.fixdep.o.cmd
remains, due to circular dependencies of fixdep on itself.
Such incomplete .cmd files don't usually cause a direct problem, since
they're designed to fail "open", but they can cause some subtle problems
that would otherwise be handled by proper fixdep'd dependency files. [2]
[1] This problem is better described in commit abb26210a3 ("perf
tools: Force fixdep compilation at the start of the build"). I don't
apply its solution here, because additional recursive make can be a bit
of overkill.
[2] Example failure case:
cp -arl linux-src linux-src2
cd linux-src2
make O=/path/to/out
cd ../linux-src
rm -rf ../linux-src2
make O=/path/to/out
Previously, we'd see errors like:
make[6]: *** No rule to make target
'/path/to/linux-src2/tools/include/linux/compiler.h', needed by
'/path/to/out/tools/bpf/resolve_btfids/libsubcmd/exec-cmd.o'. Stop.
Now, the properly-fixdep'd .cmd files will ignore a missing
/path/to/linux-src2/...
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/ZGVi9HbI43R5trN8@bhelgaas/
Link: https://lore.kernel.org/all/Zk-C5Eg84yt6_nml@google.com/
Link: https://lore.kernel.org/r/20240715203325.3832977-2-briannorris@chromium.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.