From: Arnaldo Carvalho de Melo <a...@redhat.com>
When building tools/lib/bpf as part of the tools/perf/ build process,
which will happend when we introduce a patch wiring that up, we end up
stomping on the feature detection caching mechanism, that uses a file in
the output directory (O=) that is shared by libbpf and perf to check if
something changed from one build to another that requires redoing the
feature detection process.
By using the recently introduced FEATURE_USER tools/build/ knob, we can
avoid that:
Before, every make invokation would run the feature detection:
$ make O=/tmp/build/perf -C tools/perf
make: Entering directory '/home/git/linux/tools/perf'
Auto-detecting system features:
... dwarf: [ on ]
... glibc: [ on ]
<SNIP>
... get_cpuid: [ on ]
... bpf: [ on ]
GEN perf-archive
GEN perf-with-kcore
Auto-detecting system features:
... libelf: [ on ]
... bpf: [ on ]
<SNIP>
After:
$ make O=/tmp/build/perf -C tools/perf
make: Entering directory '/home/git/linux/tools/perf'
BUILD: Doing 'make -j4' parallel build
make: Leaving directory '/home/git/linux/tools/perf'
$
Because we now have two different feature detection state files:
$ ls -la /tmp/build/perf/FEATURE-DUMP*
-rw-rw-r--. 1 acme acme 338 Sep 21 17:25 /tmp/build/perf/FEATURE-DUMP
-rw-rw-r--. 1 acme acme 33 Sep 21 17:25 /tmp/build/perf/FEATURE-DUMP.libbpf
$
Acked-by: Jiri Olsa <jo...@kernel.org>
Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: Alexei Starovoitov <a...@plumgrid.com>
Cc: Borislav Petkov <b...@suse.de>
Cc: David Ahern <dsah...@gmail.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Wang Nan <wangn...@huawei.com>
Cc: pi3or...@163.com
Fixes: 1b76c13e4b36 ("bpf tools: Introduce 'bpf' library and add bpf feature
check")
Link: http://lkml.kernel.org/n/tip-s6ev9wfqy7pvvs58emys2...@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
tools/lib/bpf/Makefile | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 604c12081b4b..e630f9fc4fb6 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -64,6 +64,7 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
#$(info Determined 'srctree' to be $(srctree))
endif
+FEATURE_USER = .libbpf
FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf
FEATURE_DISPLAY = libelf bpf
--
2.1.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
