linux/tools/build
Arnaldo Carvalho de Melo 11c6cbe706 tools build feature: Check if eventfd() is available
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.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-11-21 22:25:44 -03:00
..
Documentation tools build: Add CFLAGS_REMOVE_* support 2016-11-14 11:37:25 -03:00
feature tools build feature: Check if eventfd() is available 2018-11-21 22:25:44 -03:00
tests License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
.gitignore perf build: Add fixdep to .gitignore 2015-10-20 10:43:28 -03:00
Build tools build: Make fixdep a hostprog 2016-10-03 11:40:35 -03:00
Build.include kbuild: Rename HOSTCFLAGS to KBUILD_HOSTCFLAGS 2018-07-18 01:18:05 +09:00
fixdep.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile kbuild: Rename HOSTLDFLAGS to KBUILD_HOSTLDFLAGS 2018-07-18 01:18:05 +09:00
Makefile.build License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile.feature tools build feature: Check if eventfd() is available 2018-11-21 22:25:44 -03:00
Makefile.include perf build: Add special fixdep cleaning rule 2017-02-17 16:04:38 -03:00