Commit-ID: 65f041bee7838e2a91dbbc0a917d9291adbb3484
Gitweb: http://git.kernel.org/tip/65f041bee7838e2a91dbbc0a917d9291adbb3484
Author: Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Mon, 21 Sep 2015 17:25:27 -0300
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Tue, 22 Sep 2015 10:47:05 -0300
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 <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Wang Nan <[email protected]>
Cc: [email protected]
Fixes: 1b76c13e4b36 ("bpf tools: Introduce 'bpf' library and add bpf feature
check")
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/lib/bpf/Makefile | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 604c120..e630f9f 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
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