RTEMS 4.5.0 On-Line Library

CPU Initialization CPU Dependent Configuration Table

RTEMS Porting Guide

4.2: CPU Dependent Configuration Table

The CPU Dependent Configuration Table contains information which tailors the behavior of RTEMS base Some of the fields in this table are required to be present in all ports of RTEMS. These fields appear at the beginning of the data structure. Fields past this point may be CPU family and CPU model dependent. For example, a port may add a field to specify the default value for an interrupt mask register on the CPU. This table is initialized by the Board Support Package and passed to the rtems_initialize_executive or rtems_initialize_executive_early directive.

typedef struct {
  void       (*pretasking_hook)( void );
  void       (*predriver_hook)( void );
  void       (*postdriver_hook)( void );
  void       (*idle_task)( void );
  boolean      do_zero_of_workspace;
  unsigned32   idle_task_stack_size;
  unsigned32   interrupt_stack_size;
  unsigned32   extra_mpci_receive_server_stack;
  void *     (*stack_allocate_hook)( unsigned32 );
  void       (*stack_free_hook)( void* );
  /* end of fields required on all CPUs */

  unsigned32   some_other_cpu_dependent_info;
}   rtems_cpu_table;

pretasking_hook: is the address of the user provided routine which is invoked once RTEMS APIs are initialized. This routine will be invoked before any system tasks are created. Interrupts are disabled. This field may be NULL to indicate that the hook is not utilized.
predriver_hook: is the address of the user provided routine that is invoked immediately before the the device drivers and MPCI are initialized. RTEMS initialization is complete but interrupts and tasking are disabled. This field may be NULL to indicate that the hook is not utilized.
postdriver_hook: is the address of the user provided routine that is invoked immediately after the the device drivers and MPCI are initialized. RTEMS initialization is complete but interrupts and tasking are disabled. This field may be NULL to indicate that the hook is not utilized.
idle_task: is the address of the optional user provided routine which is used as the system's IDLE task. If this field is not NULL, then the RTEMS default IDLE task is not used. This field may be NULL to indicate that the default IDLE is to be used.
do_zero_of_workspace: indicates whether RTEMS should zero the Workspace as part of its initialization. If set to TRUE, the Workspace is zeroed. Otherwise, it is not.
idle_task_stack_size: is the size of the RTEMS idle task stack in bytes. If this number is less than MINIMUM_STACK_SIZE, then the idle task's stack will be MINIMUM_STACK_SIZE in byte.
interrupt_stack_size: is the size of the RTEMS allocated interrupt stack in bytes. This value must be at least as large as MINIMUM_STACK_SIZE.
extra_mpci_receive_server_stack: is the extra stack space allocated for the RTEMS MPCI receive server task in bytes. The MPCI receive server may invoke nearly all directives and may require extra stack space on some targets.
stack_allocate_hook: is the address of the optional user provided routine which allocates memory for task stacks. If this hook is not NULL, then a stack_free_hook must be provided as well.
stack_free_hook: is the address of the optional user provided routine which frees memory for task stacks. If this hook is not NULL, then a stack_allocate_hook must be provided as well.

RTEMS Porting Guide