From: Olivier Matz <olivier.matz@6wind.com>
Date: Fri, 27 Jan 2017 14:23:17 +0000 (+0100)
Subject: efd: fix build by removing dependency to libmath
X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=cb8fac62beb741e4fdacb41be2b242e964b75f73;hp=7eb8895d405b6e5d76259faf524459030c8b8232;p=dpdk.git

efd: fix build by removing dependency to libmath

When we compile the dpdk with:
  CONFIG_RTE_LIBRTE_EFD=y
  CONFIG_RTE_LIBRTE_NFP_PMD=n
  CONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD=n
  CONFIG_RTE_LIBRTE_SCHED=n
  CONFIG_RTE_LIBRTE_METER=n

The linker gives the following error:
  lib/librte_efd.a(rte_efd.o): In function `rte_efd_create':
  lib/librte_efd/rte_efd.c:560: undefined reference to `log2'
  collect2: error: ld returned 1 exit status

This is because the '-lm' is missing in mk/rte.app.mk.

An alternative, which is proposed by this patch, is to use the compiler
builtin rte_bsf32() to process log2 instead of the libmath log2() that
requires to include math.h and link with -lm.

Fixes: 56b6ef874f80 ("efd: new Elastic Flow Distributor library")

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
---

diff --git a/lib/librte_efd/Makefile b/lib/librte_efd/Makefile
index 8848c58623..a442c6260c 100644
--- a/lib/librte_efd/Makefile
+++ b/lib/librte_efd/Makefile
@@ -34,8 +34,6 @@ include $(RTE_SDK)/mk/rte.vars.mk
 # library name
 LIB = librte_efd.a
 
-LDLIBS += -lm
-
 CFLAGS += -O3
 CFLAGS += $(WERROR_FLAGS) -I$(SRCDIR)
 
diff --git a/lib/librte_efd/rte_efd.c b/lib/librte_efd/rte_efd.c
index 68e6dab02d..f601d62e32 100644
--- a/lib/librte_efd/rte_efd.c
+++ b/lib/librte_efd/rte_efd.c
@@ -36,7 +36,6 @@
 #include <inttypes.h>
 #include <errno.h>
 #include <stdarg.h>
-#include <math.h>
 #include <sys/queue.h>
 
 #include <rte_log.h>
@@ -557,7 +556,7 @@ rte_efd_create(const char *name, uint32_t max_num_rules, uint32_t key_len,
 		num_chunks = rte_align32pow2((max_num_rules /
 			EFD_TARGET_CHUNK_NUM_RULES) + 1);
 
-	num_chunks_shift = log2(num_chunks);
+	num_chunks_shift = rte_bsf32(num_chunks);
 
 	rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);