RTEMS 4.8.1 On-Line Library

Intel/AMD x86 Specific Information CPU Dependent Information Table

RTEMS CPU Architecture Supplement

3.7.1: CPU Dependent Information Table

The i386 version of the RTEMS CPU Dependent Information Table contains the information required to interface a Board Support Package and RTEMS on the i386. This information is provided to allow RTEMS to interoperate effectively with the BSP. The C structure definition is given here:

typedef struct {
  void       (*pretasking_hook)( void );
  void       (*predriver_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   interrupt_segment;
  void        *interrupt_vector_table;
} 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.
interrupt_segment: is the value of the selector which should be placed in a segment register to access the Interrupt Descriptor Table.
interrupt_vector_table: is the base address of the Interrupt Descriptor Table relative to the interrupt_segment.

The contents of the i386 Interrupt Descriptor Table are discussed in Intel's i386 User's Manual. Structure definitions for the i386 IDT is provided by including the file rtems.h.

RTEMS CPU Architecture Supplement