• Arnaldo Carvalho de Melo's avatar
    tools build feature: Check if eventfd() is available · 11c6cbe7
    Arnaldo Carvalho de Melo authored
    A new 'perf bench epoll' will use this, and to disable it for older
    systems, add a feature test for this API.
    
    This is just a simple program that if successfully compiled, means that
    the feature is present, at least at the library level, in a build that
    sets the output directory to /tmp/build/perf (using O=/tmp/build/perf),
    we end up with:
    
      $ ls -la /tmp/build/perf/feature/test-eventfd*
      -rwxrwxr-x. 1 acme acme 8176 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.bin
      -rw-rw-r--. 1 acme acme  588 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.d
      -rw-rw-r--. 1 acme acme    0 Nov 21 15:58 /tmp/build/perf/feature/test-eventfd.make.output
      $ ldd /tmp/build/perf/feature/test-eventfd.bin
    	  linux-vdso.so.1 (0x00007fff3bf3f000)
    	  libc.so.6 => /lib64/libc.so.6 (0x00007fa984061000)
    	  /lib64/ld-linux-x86-64.so.2 (0x00007fa984417000)
      $ grep eventfd -A 2 -B 2 /tmp/build/perf/FEATURE-DUMP
      feature-dwarf=1
      feature-dwarf_getlocations=1
      feature-eventfd=1
      feature-fortify-source=1
      feature-sync-compare-and-swap=1
      $
    
    The main thing here is that in the end we'll have -DHAVE_EVENTFD in
    CFLAGS, and then the 'perf bench' entry needing that API can be
    selectively pruned.
    
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Davidlohr Bueso <dbueso@suse.de>
    Cc: Jason Baron <jbaron@akamai.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Wang Nan <wangnan0@huawei.com>
    Link: https://lkml.kernel.org/n/tip-wkeldwob7dpx6jvtuzl8164k@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    11c6cbe7
Makefile.feature 7.79 KB