eal: fix build with glibc < 2.12

build error:
  CC rte_cycles.o
  cc1: warnings being treated as errors
  ...dpdk/lib/librte_eal/common/arch/x86/rte_cycles.c: In function
  ‘rdmsr’:
  ...dpdk/lib/librte_eal/common/arch/x86/rte_cycles.c:67:2: error:
  implicit declaration of function ‘pread’
  ...dpdk/lib/librte_eal/common/arch/x86/rte_cycles.c:67:2: error:
  nested extern declaration of ‘pread’

from pread man page:
pread(), pwrite():
   _XOPEN_SOURCE >= 500
   || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L

For glibc < 2.12 _XOPEN_SOURCE >= 500 is required.

Adding _GNU_SOURCE define to the file which implies _XOPEN_SOURCE=700

Fixes: ad3516bb4ae1 ("eal/x86: implement arch-specific TSC freq query")

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>

diff --git a/lib/librte_eal/linuxapp/eal/Makefile b/lib/librte_eal/linuxapp/eal/Makefile
index 965da6e..edfb8ff 100644 (file)
--- a/lib/librte_eal/linuxapp/eal/Makefile
+++ b/lib/librte_eal/linuxapp/eal/Makefile
@@ -139,6 +139,7 @@ CFLAGS_eal_common_whitelist.o := -D_GNU_SOURCE
 CFLAGS_eal_common_options.o := -D_GNU_SOURCE
 CFLAGS_eal_common_thread.o := -D_GNU_SOURCE
 CFLAGS_eal_common_lcore.o := -D_GNU_SOURCE
+CFLAGS_rte_cycles.o := -D_GNU_SOURCE
 
 # workaround for a gcc bug with noreturn attribute
 # http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12603