Subject: Re: [PATCH v3 1/4] perf: Add capability-related utilities

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Mon, 12 Aug 2019 16:43:02 -0300

Em Wed, Aug 07, 2019 at 10:44:14AM -0400, Igor Lubashev escreveu:
> Add utilities to help checking capabilities of the running procss.
> Make perf link with libcap, if it is available. If no libcap-dev[el],
> assume no capabilities.

Applied and added the text at the end of this message on the commit log,
I'm also adding NO_LIBCAP=1 to the minimum build in

  make -C tools/perf build-test

I.e.:

diff --git a/tools/perf/tests/make b/tools/perf/tests/make
index 5363a12a8b9b..70c48475896d 100644
--- a/tools/perf/tests/make
+++ b/tools/perf/tests/make
@@ -108,6 +108,7 @@ make_minimal        += NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1
 make_minimal        += NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1
 make_minimal        += NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1
 make_minimal        += NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1 NO_LIBZSTD=1
+make_minimal        += NO_LIBCAP=1
 
 # $(run) contains all available tests
 run := make_pure

Thanks,

- Arnaldo

Committer testing:

  $ make O=/tmp/build/perf -C tools/perf install-bin
  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j8' parallel build
  
  Auto-detecting system features:
  <SNIP>
  ...                        libbfd: [ on  ]
  ...                        libcap: [ OFF ]
  ...                        libelf: [ on  ]
  <SNIP>
  Makefile.config:833: No libcap found, disables capability support, please install libcap-devel/libcap-dev
  <SNIP>
  $ grep libcap /tmp/build/perf/FEATURE-DUMP 
  feature-libcap=0
  $ cat /tmp/build/perf/feature/test-libcap.make.output 
  test-libcap.c:2:10: fatal error: sys/capability.h: No such file or directory
      2 | #include <sys/capability.h>
        |          ^~~~~~~~~~~~~~~~~~
  compilation terminated.
  $

Now install libcap-devel and try again:

  $ make O=/tmp/build/perf -C tools/perf install-bin
  make: Entering directory '/home/acme/git/perf/tools/perf'
    BUILD:   Doing 'make -j8' parallel build
  Warning: Kernel ABI header at 'tools/include/linux/bits.h' differs from latest version at 'include/linux/bits.h'
  diff -u tools/include/linux/bits.h include/linux/bits.h
  Warning: Kernel ABI header at 'tools/arch/x86/include/asm/cpufeatures.h' differs from latest version at 'arch/x86/include/asm/cpufeatures.h'
  diff -u tools/arch/x86/include/asm/cpufeatures.h arch/x86/include/asm/cpufeatures.h
  
  Auto-detecting system features:
  ...                         dwarf: [ on  ]
  ...            dwarf_getlocations: [ on  ]
  ...                         glibc: [ on  ]
  ...                          gtk2: [ on  ]
  ...                      libaudit: [ on  ]
  ...                        libbfd: [ on  ]
  ...                        libcap: [ on  ]
  ...                        libelf: [ on  ]
  <SNIP>>
    CC       /tmp/build/perf/jvmti/libjvmti.o
  <SNIP>>
  $ grep libcap /tmp/build/perf/FEATURE-DUMP 
  feature-libcap=1
  $ cat /tmp/build/perf/feature/test-libcap.make.output 
  $ ldd /tmp/build/perf/feature/test-libcap.make.bin
  ldd: /tmp/build/perf/feature/test-libcap.make.bin: No such file or directory
  $ ldd /tmp/build/perf/feature/test-libcap.bin 
  	linux-vdso.so.1 (0x00007ffc35bfe000)
  	libcap.so.2 => /lib64/libcap.so.2 (0x00007ff9c62ff000)
  	libc.so.6 => /lib64/libc.so.6 (0x00007ff9c6139000)
  	/lib64/ld-linux-x86-64.so.2 (0x00007ff9c6326000)
  $
  $ ldd ~/bin/perf | grep libcap
	libcap.so.2 => /lib64/libcap.so.2 (0x00007fe20ea19000)
  $

Signed-off-by: Igor Lubashev <[email-masked]>
Acked-by: Jiri Olsa <[email-masked]>
Tested-by: Arnaldo Carvalho de Melo <[email-masked]>

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