pthreads: Add support static pthread stack. Add standard pthread_attr_setstack() and pthread_attr_getstack(). In all cases where the stack is released, add check to see which allocator must be used to free the stack: The user or the kernel allocator.

include/nuttx/pthread.h

@@ -71,6 +71,7 @@
     0,                        /* low_priority */ \
     0,                        /* max_repl */ \
     0,                        /* affinity */ \
+    NULL,                     /* stackaddr */ \
     PTHREAD_STACK_DEFAULT,    /* stacksize */ \
     {0, 0},                   /* repl_period */ \
     {0, 0}                    /* budget */ \
@@ -83,6 +84,7 @@
     PTHREAD_EXPLICIT_SCHED,   /* inheritsched */ \
     0,                        /* low_priority */ \
     0,                        /* max_repl */ \
+    NULL,                     /* stackaddr */ \
     PTHREAD_STACK_DEFAULT,    /* stacksize */ \
     {0, 0},                   /* repl_period */ \
     {0, 0},                   /* budget */ \
@@ -94,6 +96,7 @@
     PTHREAD_DEFAULT_POLICY,   /* policy */ \
     PTHREAD_EXPLICIT_SCHED,   /* inheritsched */ \
     0,                        /* affinity */ \
+    NULL,                     /* stackaddr */ \
     PTHREAD_STACK_DEFAULT,    /* stacksize */ \
   }
 #else
@@ -102,6 +105,7 @@
     PTHREAD_DEFAULT_PRIORITY, /* priority */ \
     PTHREAD_DEFAULT_POLICY,   /* policy */ \
     PTHREAD_EXPLICIT_SCHED,   /* inheritsched */ \
+    NULL,                     /* stackaddr */ \
     PTHREAD_STACK_DEFAULT,    /* stacksize */ \
   }
 #endif

include/pthread.h

@@ -227,6 +227,7 @@ struct pthread_attr_s
   cpu_set_t affinity;          /* Set of permitted CPUs for the thread */
 #endif
 
+  FAR void  *stackaddr;        /* Address of memory to be used as stack */
   size_t stacksize;            /* Size of the stack allocated for the pthread */
 
 #ifdef CONFIG_SCHED_SPORADIC
@@ -406,6 +407,13 @@ int pthread_attr_getaffinity_np(FAR const pthread_attr_t *attr,
 int pthread_attr_setstacksize(FAR pthread_attr_t *attr, long stacksize);
 int pthread_attr_getstacksize(FAR const pthread_attr_t *attr, long *stackaddr);
 
+/* Set or obtain stack address and size */
+
+int pthread_attr_setstack(FAR pthread_attr_t *attr,
+                          FAR void *stackaddr, long stacksize);
+int pthread_attr_getstack(FAR pthread_attr_t *attr,
+                          FAR void **stackaddr, FAR long *stacksize);
+
 /* To create a thread object and runnable thread, a routine must be specified
  * as the new thread's start routine.  An argument may be passed to this
  * routine, as an untyped address; an untyped address may also be returned as