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authorArnaldo Carvalho de Melo <acme@redhat.com>2015-09-21 17:25:27 -0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-09-22 10:47:05 -0300
commit65f041bee7838e2a91dbbc0a917d9291adbb3484 (patch)
treee619c2f8b6b716d80c18b1d1bdb25085038a4091 /tools/lib
parent13e96db61c1c32cd4c8102a95129bb7677cc746d (diff)
tools lib bpf: Use FEATURE_USER to allow building in the same dir as perf
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 <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Borislav Petkov <bp@suse.de> Cc: David Ahern <dsahern@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Stephane Eranian <eranian@google.com> Cc: Wang Nan <wangnan0@huawei.com> Cc: pi3orama@163.com Fixes: 1b76c13e4b36 ("bpf tools: Introduce 'bpf' library and add bpf feature check") Link: http://lkml.kernel.org/n/tip-s6ev9wfqy7pvvs58emys2g90@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/Makefile1
1 files changed, 1 insertions, 0 deletions
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