[PATCH v6 25/30] lib/eal: replace packed attributes

[Andre Muezerie <andremue@linux.microsoft.com>]

MSVC struct packing is not compatible with GCC. Replace macro
__rte_packed with __rte_packed_begin to push existing pack value
and set packing to 1-byte and macro __rte_packed_end to restore
the pack value prior to the push.

Macro __rte_packed_end is deliberately utilized to trigger a
MSVC compiler warning if no existing packing has been pushed allowing
easy identification of locations where the __rte_packed_begin is
missing.

Removed the packed attributes from some structures that don't need
them.

Signed-off-by: Andre Muezerie <andremue@linux.microsoft.com>
---
 lib/eal/common/eal_private.h      | 2 +-
 lib/eal/include/rte_memory.h      | 3 ++-
 lib/eal/include/rte_memzone.h     | 3 ++-
 lib/eal/include/rte_trace_point.h | 2 +-
 lib/eal/x86/include/rte_memcpy.h  | 9 ++++++---
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/lib/eal/common/eal_private.h b/lib/eal/common/eal_private.h
index bb315dab04..3b94e01b5b 100644
--- a/lib/eal/common/eal_private.h
+++ b/lib/eal/common/eal_private.h
@@ -62,7 +62,7 @@ struct rte_config {
 	 * DPDK instances
 	 */
 	struct rte_mem_config *mem_config;
-} __rte_packed;
+};
 
 /**
  * Get the global configuration structure.
diff --git a/lib/eal/include/rte_memory.h b/lib/eal/include/rte_memory.h
index dbd0a6bedc..25fd7e0a6b 100644
--- a/lib/eal/include/rte_memory.h
+++ b/lib/eal/include/rte_memory.h
@@ -46,6 +46,7 @@ extern "C" {
 /**
  * Physical memory segment descriptor.
  */
+__rte_packed_begin
 struct rte_memseg {
 	rte_iova_t iova;            /**< Start IO address. */
 	union {
@@ -58,7 +59,7 @@ struct rte_memseg {
 	uint32_t nchannel;          /**< Number of channels. */
 	uint32_t nrank;             /**< Number of ranks. */
 	uint32_t flags;             /**< Memseg-specific flags */
-} __rte_packed;
+} __rte_packed_end;
 
 /**
  * memseg list is a special case as we need to store a bunch of other data
diff --git a/lib/eal/include/rte_memzone.h b/lib/eal/include/rte_memzone.h
index e1563994d5..28c2262e12 100644
--- a/lib/eal/include/rte_memzone.h
+++ b/lib/eal/include/rte_memzone.h
@@ -45,6 +45,7 @@ extern "C" {
  * A structure describing a memzone, which is a contiguous portion of
  * physical memory identified by a name.
  */
+__rte_packed_begin
 struct rte_memzone {
 
 #define RTE_MEMZONE_NAMESIZE 32       /**< Maximum length of memory zone name.*/
@@ -62,7 +63,7 @@ struct rte_memzone {
 	int32_t socket_id;                /**< NUMA socket ID. */
 
 	uint32_t flags;                   /**< Characteristics of this memzone. */
-} __rte_packed;
+} __rte_packed_end;
 
 /**
  * Set the maximum number of memzones.
diff --git a/lib/eal/include/rte_trace_point.h b/lib/eal/include/rte_trace_point.h
index 87b5f43c3c..b24db3b6da 100644
--- a/lib/eal/include/rte_trace_point.h
+++ b/lib/eal/include/rte_trace_point.h
@@ -298,7 +298,7 @@ struct __rte_trace_stream_header {
 	rte_uuid_t uuid;
 	uint32_t lcore_id;
 	char thread_name[__RTE_TRACE_EMIT_STRING_LEN_MAX];
-} __rte_packed;
+};
 
 struct __rte_trace_header {
 	uint32_t offset;
diff --git a/lib/eal/x86/include/rte_memcpy.h b/lib/eal/x86/include/rte_memcpy.h
index 42058e4a3f..58368145c4 100644
--- a/lib/eal/x86/include/rte_memcpy.h
+++ b/lib/eal/x86/include/rte_memcpy.h
@@ -67,15 +67,18 @@ rte_mov15_or_less(void *dst, const void *src, size_t n)
 	 * Use the following structs to avoid violating C standard
 	 * alignment requirements and to avoid strict aliasing bugs
 	 */
+	__rte_packed_begin
 	struct rte_uint64_alias {
 		uint64_t val;
-	} __rte_packed __rte_may_alias;
+	} __rte_packed_end __rte_may_alias;
+	__rte_packed_begin
 	struct rte_uint32_alias {
 		uint32_t val;
-	} __rte_packed __rte_may_alias;
+	} __rte_packed_end __rte_may_alias;
+	__rte_packed_begin
 	struct rte_uint16_alias {
 		uint16_t val;
-	} __rte_packed __rte_may_alias;
+	} __rte_packed_end __rte_may_alias;
 
 	void *ret = dst;
 	if (n & 8) {
-- 
2.34.1