[dpdk-dev] [PATCH 1/2] eal:Introduce rte_dma_wmb/rte_dma_rmb.

[WangDong <dong.wang.pro@hotmail.com>]

These macro can be used to replace current PMD's compiler memory barrier (volatile varible) and rte_wmb.
In x86, they implement to compiler memory barrier.
In power, they implement to processor memory barrier.

---
 .../common/include/arch/ppc_64/rte_atomic.h        |  4 ++++
 .../common/include/arch/x86/rte_atomic.h           |  4 ++++
 lib/librte_eal/common/include/generic/rte_atomic.h | 25 ++++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
index fb7af2b..8f4129d 100644
--- a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
+++ b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
@@ -72,6 +72,10 @@ extern "C" {
  */
 #define	rte_rmb() {asm volatile("sync" : : : "memory"); }
 
+#define rte_dma_wmb() {asm volatile("sync" : : : "memory"); }
+
+#define rte_dma_rmb() {asm volatile("sync" : : : "memory"); 
+
 /*------------------------- 16 bit atomic operations -------------------------*/
 /* To be compatible with Power7, use GCC built-in functions for 16 bit
  * operations */
diff --git a/lib/librte_eal/common/include/arch/x86/rte_atomic.h b/lib/librte_eal/common/include/arch/x86/rte_atomic.h
index e93e8ee..7cfbe8f 100644
--- a/lib/librte_eal/common/include/arch/x86/rte_atomic.h
+++ b/lib/librte_eal/common/include/arch/x86/rte_atomic.h
@@ -53,6 +53,10 @@ extern "C" {
 
 #define	rte_rmb() _mm_lfence()
 
+#define rte_dma_wmb() rte_compiler_barrier()
+
+#define rte_dma_rmb() rte_compiler_barrier()
+
 /*------------------------- 16 bit atomic operations -------------------------*/
 
 #ifndef RTE_FORCE_INTRINSICS
diff --git a/lib/librte_eal/common/include/generic/rte_atomic.h b/lib/librte_eal/common/include/generic/rte_atomic.h
index 6c7581a..a51eeee 100644
--- a/lib/librte_eal/common/include/generic/rte_atomic.h
+++ b/lib/librte_eal/common/include/generic/rte_atomic.h
@@ -72,6 +72,31 @@ static inline void rte_wmb(void);
  */
 static inline void rte_rmb(void);
 
+/**
+ * Write memory barrier for DMA.
+ *
+ * Be used in PMD, unlike rte_wmb() which use processor memory barrier,
+ * this memory barrier focus on performance, if compiler memory barrier
+ * is sufficient for guarantee memory ordering, this function will
+ * use compiler memory barrier.
+ *
+ * This function is architecture dependent.
+ */
+static inline void rte_dma_wmb(void);
+
+/**
+ * Read memory barrier for DMA.
+ *
+ * Be used in PMD, unlike rte_rmb() which use processor memory barrier,
+ * this memory barrier focus on performance, if compiler memory barrier
+ * is sufficient for guarantee memory ordering, this function will
+ * use compiler memory barrier.
+ *
+ * This function is architecture dependent.
+ */
+static inline void rte_dma_rmb(void);
+
+
 #endif /* __DOXYGEN__ */
 
 /**
-- 
2.1.0