Idle Task Configuration

Macros
#define	CONFIGURE_IDLE_TASK_BODY
	This configuration option is an initializer define. More...
#define	CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION
	This configuration option is a boolean feature define. More...
#define	CONFIGURE_IDLE_TASK_STACK_SIZE
	This configuration option is an integer define. More...

Detailed Description

This section describes configuration options related to the idle tasks.

Macro Definition Documentation

CONFIGURE_IDLE_TASK_BODY

#define CONFIGURE_IDLE_TASK_BODY

This configuration option is an initializer define.

The value of this configuration option initializes the IDLE thread body.

Default Value

If BSP_IDLE_TASK_BODY is defined, then this will be the default value, otherwise the default value is _CPU_Thread_Idle_body.

Value Constraints

The value of this configuration option shall be defined to a valid function pointer of the type void *( *idle_body )( uintptr_t ).

Notes

IDLE threads shall not block. A blocking IDLE thread results in undefined system behaviour because the scheduler assume that at least one ready thread exists.

IDLE threads can be used to initialize the application, see configuration option CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION.

Definition at line 3147 of file appl-config.h.

CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION

#define CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION

This configuration option is a boolean feature define.

This configuration option is defined to indicate that the user has configured no user initialization tasks or threads and that the user provided IDLE task will perform application initialization and then transform itself into an IDLE task.

Default Configuration

If this configuration option is undefined, then the user is assumed to provide one or more initialization tasks.

Notes

If you use this option be careful, the user IDLE task cannot block at all during the initialization sequence. Further, once application initialization is complete, it shall make itself preemptible and enter an idle body loop.

The IDLE task shall run at the lowest priority of all tasks in the system.

If this configuration option is defined, then it is mandatory to configure a user IDLE task with the CONFIGURE_IDLE_TASK_BODY configuration option, otherwise a compile time error in the configuration file will occur.

The application shall define exactly one of the following configuration options

• CONFIGURE_RTEMS_INIT_TASKS_TABLE,
• CONFIGURE_POSIX_INIT_THREAD_TABLE, or
• CONFIGURE_IDLE_TASK_INITIALIZES_APPLICATION

otherwise a compile time error in the configuration file will occur.

Definition at line 3188 of file appl-config.h.

CONFIGURE_IDLE_TASK_STACK_SIZE

#define CONFIGURE_IDLE_TASK_STACK_SIZE

This configuration option is an integer define.

The value of this configuration option defines the task stack size for an IDLE task.

Default Value

The default value is CONFIGURE_MINIMUM_TASK_STACK_SIZE.

Value Constraints

The value of this configuration option shall satisfy all of the following constraints:

• It shall be greater than or equal to a BSP-specific and application-specific minimum value.
• It shall be small enough so that the IDLE task stack area calculation carried out by <rtems/confdefs.h> does not overflow an integer of type size_t.

Notes

In SMP configurations, there is one IDLE task per configured processor, see CONFIGURE_MAXIMUM_PROCESSORS.

Definition at line 3218 of file appl-config.h.