microkernel: Don't initialize packets in a command packet set

Reworks the internal design of a command packet set so that
the command packet array is split out into a separate variable
lying in uninitialized memory. This shrinks the command packet's
data section footprint to almost nothing.

Note: A side effect of this change is that it is no longer possible
to define a command packet set as a "static" variable since the
CMD_PKT_SET_INSTANCE() macro now generates two variables.

Change-Id: I9c7ebe637edf879758589ff4a26ace1303790bf7
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>

include/microkernel/command_packet.h

@@ -28,8 +28,8 @@
  * Each command packet set is created in global memory using ...
  *   CMD_PKT_SET_INSTANCE(set variable name, # of command packets in the set);
  *
- * Once created, the command packet set is accessed using ...
- *   CMD_PKT_SET(set variable name).<member field name>
+ * Once created, the command packet set is referenced as an ordinary structured
+ * variable.
 
  * A command packet set is a simple ring buffer.  No error checking is performed
  * when a command packet is retrieved from the set.  Each obtained command packet
@@ -52,47 +52,34 @@ extern "C" {
 
 #define CMD_PKT_SIZE_IN_WORDS (19)
 
-/**
- * @brief Define a command packet set
- *
- *
- * This macro is used to create a command packet set in the global namespace.
- * Each packet set can have a different number of packets.
- *
- * @param name Name of command packet set
- * @param num Number of packets in the set
- *
- * @internal
- * It is critical that the word corresponding to the [alloc] field in the
- * equivalent struct k_args command packet be zero so that the system knows that the
- * command packet is not part of the free list.
- * @endinternal
- */
-#define CMD_PKT_SET_INSTANCE(name, num) \
-	uint32_t name[2 + CMD_PKT_SIZE_IN_WORDS * (num)] = {num, 0}
-
-/**
- * @brief Wrapper for accessing a command packet set
- *
- * A command packet set must be typecast to the cmd_pkt_set type
- * when accessed, because it is instantiated as an array of uint32_t.
- *
- * @param name Name of command packet set
- *
- */
-#define CMD_PKT_SET(name) (*(struct cmd_pkt_set *)(name))
+/* define command packet set types */
 
 typedef uint32_t cmdPkt_t[CMD_PKT_SIZE_IN_WORDS];
 
 struct cmd_pkt_set {
 	uint32_t num_packets;      /* number of command packets in set */
 	uint32_t index;            /* index into command packet array */
-	cmdPkt_t command_packet[]; /* array of command packets */
+	cmdPkt_t *command_packet;  /* pointer to array of command packets */
 };
 
+/**
+ * @brief Define a command packet set
+ *
+ * This macro is used to create a command packet set of the specified size.
+ *
+ * @param name Name of command packet set
+ * @param num Number of packets in the set
+ *
+ * @warning The command packet set exists in the global namespace,
+ * and cannot be hidden by prefixing the macro with "static".
+ */
+#define CMD_PKT_SET_INSTANCE(name, num) \
+	uint32_t __noinit (_k_cmd_pkts_ ## name)[CMD_PKT_SIZE_IN_WORDS * (num)]; \
+	struct cmd_pkt_set name = {(num), 0, (cmdPkt_t *)(_k_cmd_pkts_ ## name)}
+
 /* externs */
 
-extern cmdPkt_t *_cmd_pkt_get(struct cmd_pkt_set *pSet);
+extern struct k_args *_cmd_pkt_get(struct cmd_pkt_set *pSet);
 
 #ifdef __cplusplus
 }

kernel/microkernel/k_command_packet.c

@@ -40,10 +40,17 @@ uint32_t _k_test_cmd_pkt_size
  * @param pSet Pointer to set of command packets
  *
  * @return pointer to the command packet
+ *
+ * @internal
+ * It is critical that the word corresponding to the [alloc] field in the
+ * equivalent struct k_args command packet be zero so that the system knows the
+ * command packet is not part of the free list.
+ * @endinternal
  */
-cmdPkt_t *_cmd_pkt_get(struct cmd_pkt_set *pSet)
+struct k_args *_cmd_pkt_get(struct cmd_pkt_set *pSet)
 {
 	uint32_t index; /* index into command packet array */
+	struct k_args *cmd_pkt; /* pointer to command packet */
 	int key;	/* interrupt lock level */
 
 	key = irq_lock();
@@ -53,7 +60,10 @@ cmdPkt_t *_cmd_pkt_get(struct cmd_pkt_set *pSet)
 		pSet->index = 0;
 	irq_unlock(key);
 
-	return &pSet->command_packet[index];
+	cmd_pkt = (struct k_args *)&pSet->command_packet[index];
+	cmd_pkt->alloc = false;
+
+	return cmd_pkt;
 }
 
 /**

kernel/microkernel/k_semaphore.c

@@ -407,13 +407,7 @@ void isr_sem_give(ksem_t sema, struct cmd_pkt_set *pSet)
 {
 	struct k_args *pCommand; /* ptr to command packet */
 
-	/*
-	 * The cmdPkt_t data structure was designed to work seamlessly with the
-	 * struct k_args data structure and it is thus safe (and expected) to typecast
-	 * the return value of _cmd_pkt_get() to "struct k_args *".
-	 */
-
-	pCommand = (struct k_args *)_cmd_pkt_get(pSet);
+	pCommand = _cmd_pkt_get(pSet);
 	pCommand->Comm = _K_SVC_SEM_SIGNAL;
 	pCommand->args.s1.sema = sema;
 

samples/microkernel/test/test_sema/src/main.c

@@ -46,7 +46,7 @@ extern struct nano_sem fiberSem; /* semaphore that allows test control the fiber
 
 static ksem_t testIsrInfo;
 
-static CMD_PKT_SET_INSTANCE(cmdPktSet, 2);
+CMD_PKT_SET_INSTANCE(cmdPktSetIsr, 2);
 
 /*
  * Note that semaphore group entries are arranged so that resultSems[TC_PASS]
@@ -167,7 +167,7 @@ void LowPriTaskEntry(void)
 
 static void testIsrHandler(void *isrData)
 {
-	isr_sem_give(*(ksem_t *)isrData, &CMD_PKT_SET(cmdPktSet));
+	isr_sem_give(*(ksem_t *)isrData, &cmdPktSetIsr);
 }
 
 /**

samples/microkernel/test/test_sema/src/test_fiber.c

@@ -38,8 +38,8 @@ extern ksem_t semList[];
 
 static char __stack fiberStack[FIBER_STACK_SIZE]; /* test fiber stack size */
 
-/* array of command packets used by test fiber to signal semaphores */
-static CMD_PKT_SET_INSTANCE(cmdPktSet, N_TESTS + 1);
+/* command packet set used by test fiber to signal semaphores */
+CMD_PKT_SET_INSTANCE(cmdPktSetFiber, N_TESTS + 1);
 
 /**
  *
@@ -59,18 +59,18 @@ static void testFiberEntry(void)
 	int i;
 	/* release semaphore test task is waiting for */
 	nano_fiber_sem_take_wait(&fiberSem);
-	fiber_sem_give(simpleSem, &CMD_PKT_SET(cmdPktSet));
+	fiber_sem_give(simpleSem, &cmdPktSetFiber);
 
 	/* release the semaphore for N_TESTS times */
 	nano_fiber_sem_take_wait(&fiberSem);
 	for (i = 0; i < N_TESTS; i++) {
-		fiber_sem_give(simpleSem, &CMD_PKT_SET(cmdPktSet));
+		fiber_sem_give(simpleSem, &cmdPktSetFiber);
 	}
 
 	/* signal each semaphore in the group */
 	for (i = 0; semList[i] != ENDLIST; i++) {
 		nano_fiber_sem_take_wait(&fiberSem);
-		fiber_sem_give(semList[i], &CMD_PKT_SET(cmdPktSet));
+		fiber_sem_give(semList[i], &cmdPktSetFiber);
 	}
 }