[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20240709204203.1481851-2-briannorris@chromium.org>
Date: Tue, 9 Jul 2024 13:41:51 -0700
From: Brian Norris <briannorris@...omium.org>
To: Arnaldo Carvalho de Melo <acme@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Peter Zijlstra <peterz@...radead.org>
Cc: linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org,
Masahiro Yamada <masahiroy@...nel.org>,
Brian Norris <briannorris@...omium.org>,
Jiri Olsa <jolsa@...nel.org>
Subject: [PATCH v3 1/3] tools build: Correct libsubcmd fixdep dependencies
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 abb26210a395 ("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/...
Link: https://lore.kernel.org/all/ZGVi9HbI43R5trN8@bhelgaas/
Link: https://lore.kernel.org/all/Zk-C5Eg84yt6_nml@google.com/
Signed-off-by: Brian Norris <briannorris@...omium.org>
Acked-by: Jiri Olsa <jolsa@...nel.org>
---
Changes in v3:
- update notes about failure cases
- add Jiri's Acked-by
tools/lib/subcmd/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/lib/subcmd/Makefile b/tools/lib/subcmd/Makefile
index b87213263a5e..59b09f280e49 100644
--- a/tools/lib/subcmd/Makefile
+++ b/tools/lib/subcmd/Makefile
@@ -76,7 +76,7 @@ include $(srctree)/tools/build/Makefile.include
all: fixdep $(LIBFILE)
-$(SUBCMD_IN): FORCE
+$(SUBCMD_IN): fixdep FORCE
@$(MAKE) $(build)=libsubcmd
$(LIBFILE): $(SUBCMD_IN)
--
2.45.2.803.g4e1b14247a-goog
Powered by blists - more mailing lists