Cosmetic: Fix all comments, defaults, etc. that references the defunct name user_start

TODO

@@ -519,13 +519,13 @@ o C++ Support
                this will provide the model for all solutions.  Basically, if
                CONFIG_HAVE_CXXINITIALIZE=y is defined in the configuration, then
                board-specific code must provide the interface up_cxxinitialize().
-               up_cxxinitialize() is called from user_start() to initialize
+               up_cxxinitialize() is called from aplication logic to initialize
                all static class instances.  This TODO item probably has to stay
                open because this solution is only available on STM32 F4.
   Status:      Open
   Priority:    Low, depends on toolchain.  Call to gcc's built-in static
                constructor logic will probably have to be performed by
-               user logic in user_start().
+               user logic in the application.
 
   Title:       STATIC CONSTRUCTORS AND MULTITASKING
   Description: The logic that calls static constructors operates on the main

drivers/usbhost/usbhost_hidkbd.c

@@ -1563,7 +1563,7 @@ static inline int usbhost_devinit(FAR struct usbhost_state_s *priv)
    * memory resources, primarily for the dedicated stack (CONFIG_HIDKBD_STACKSIZE).
    */
 
-  uvdbg("user_start: Start poll task\n");
+  uvdbg("Start poll task\n");
 
   /* The inputs to a task started by task_create() are very awkard for this
    * purpose.  They are really designed for command line tasks (argc/argv). So

drivers/usbhost/usbhost_hidmouse.c

@@ -1635,7 +1635,7 @@ static inline int usbhost_devinit(FAR struct usbhost_state_s *priv)
    * memory resources, primarily for the dedicated stack (CONFIG_HIDMOUSE_STACKSIZE).
    */
 
-  uvdbg("user_start: Start poll task\n");
+  uvdbg("Start poll task\n");
 
   /* The inputs to a task started by task_create() are very awkward for this
    * purpose.  They are really designed for command line tasks (argc/argv). So

include/nuttx/arch.h

@@ -1326,9 +1326,9 @@ void up_udelay(useconds_t microseconds);
  *   initialization of the static C++ class instances.
  *
  *   This function should then be called in the application-specific
- *   user_start logic in order to perform the C++ initialization.  NOTE
- *   that no component of the core NuttX RTOS logic is involved; This
- *   function definition only provides the 'contract' between application
+ *   logic in order to perform the C++ initialization.  NOTE  that no
+ *   component of the core NuttX RTOS logic is involved; This function
+ *   definition only provides the 'contract' between application
  *   specific C++ code and platform-specific toolchain support
  *
  ***************************************************************************/

sched/Kconfig

@@ -220,11 +220,11 @@ menu "Tasks and Scheduling"
 
 config USER_ENTRYPOINT
 	string "Application entry point"
-	default "user_start"
+	default "main"
 	---help---
 		The name of the entry point for user applications.  For the example
 		applications this is of the form 'app_main' where 'app' is the application
-		name. If not defined, USER_ENTRYPOINT defaults to "user_start."
+		name. If not defined, USER_ENTRYPOINT defaults to "main".
 
 config RR_INTERVAL
 	int "Round robin timeslice (MSEC)"
@@ -716,16 +716,16 @@ config IDLETHREAD_STACKSIZE
 	default 1024
 	---help---
 		The size of the initial stack used by the IDLE thread.  The IDLE thread
-		is the thread that (1) performs the inital boot of the system up to the
-		point where user_start() is spawned, and (2) there after is the IDLE
-		thread that executes only when there is no other thread ready to run.
+		is the thread that (1) performs the initial boot of the system up to the
+		point where start-up appliation is spawned, and (2) there after is the
+		IDLE thread that executes only when there is no other thread ready to run.
 
 config USERMAIN_STACKSIZE
 	int "Main thread stack size"
 	default 2048
 	---help---
-		The size of the stack to allocate for the main user thread that begins at
-		the user_start() entry point.
+		The size of the stack to allocate for the user initialization thread
+		that is started as soon as the OS completes its initialization.
 
 config PTHREAD_STACK_MIN
 	int "Minimum pthread stack size"

sched/init/os_bringup.c

@@ -63,8 +63,8 @@
  ****************************************************************************/
 
 /* If NuttX is built as a separately compiled module, then the config.h header
- * file should contain the address of the user module entry point.  If not
- * then the default entry point is user_start.
+ * file should contain the address of the entry point (or path to the file)
+ * that will perform the application-level initialization.
  */
 
 /* Customize some strings */

sched/init/os_start.c

@@ -207,8 +207,8 @@ const struct tasklist_s g_tasklisttable[NUM_TASK_STATES] =
  ****************************************************************************/
 /* This is the task control block for this thread of execution. This thread
  * of execution is the IDLE task.  NOTE:  the system boots into the IDLE
- * task.  The IDLE task spawns the user initialization task (user_start) and
- * that user init task is responsible for bringing up the rest of the system
+ * task.  The IDLE task spawns the user initialization task and that user
+ * initialization task is responsible for bringing up the rest of the system.
  */
 
 static FAR struct task_tcb_s g_idletcb;

tools/mkconfig.c

@@ -276,7 +276,7 @@ int main(int argc, char **argv, char **envp)
   printf(" * with existing code, for builds which do not define CONFIG_USER_ENTRYPOINT.\n");
   printf(" */\n\n");
   printf("#ifndef CONFIG_USER_ENTRYPOINT\n");
-  printf("# define CONFIG_USER_ENTRYPOINT user_start\n");
+  printf("# define CONFIG_USER_ENTRYPOINT main\n");
   printf("#endif\n\n");
   printf("#endif /* __INCLUDE_NUTTX_CONFIG_H */\n");
   fclose(stream);