26.11. POSIX API Configuration

This section describes configuration options related to the POSIX API. Most POSIX API objects are available by default since RTEMS 5.1. The queued signals and timers are only available if RTEMS was built with the enable POSIX build configuration option.

26.11.1. CONFIGURE_MAXIMUM_POSIX_KEYS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_KEYS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Keys that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

26.11.2. CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_KEY_VALUE_PAIRS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is CONFIGURE_MAXIMUM_POSIX_KEYS * ( CONFIGURE_MAXIMUM_TASKS + CONFIGURE_MAXIMUM_POSIX_THREADS ).

DESCRIPTION:

The value of this configuration option defines the maximum number of key value pairs used by POSIX API Keys that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

A key value pair is created by pthread_setspecific() if the value is not NULL, otherwise it is deleted.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

26.11.3. CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_MESSAGE_QUEUES

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Message Queues that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects. You have to account for the memory used to store the messages of each message queue, see CONFIGURE_MESSAGE_BUFFER_MEMORY.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option shall be small enough so that the RTEMS Workspace size calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

26.11.4. CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_QUEUED_SIGNALS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Queued Signals that can be concurrently active.

NOTES:

Unlimited objects are not available for queued signals.

Queued signals are only available if RTEMS was built with the POSIX API build configuration option enabled.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option shall be small enough so that the RTEMS Workspace size calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

  • The value of the configuration option shall be zero if the POSIX API is not enabled (e.g. RTEMS was built without the RTEMS_POSIX_API = True build configuration option). Otherwise a compile time error in the configuration file will occur.

26.11.5. CONFIGURE_MAXIMUM_POSIX_SEMAPHORES

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_SEMAPHORES

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Named Semaphores that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

Named semaphores are created with sem_open(). Semaphores initialized with sem_init() are not affected by this configuration option since the storage space for these semaphores is user-provided.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option shall be small enough so that the RTEMS Workspace size calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

26.11.6. CONFIGURE_MAXIMUM_POSIX_SHMS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_SHMS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Shared Memory objects that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option shall be small enough so that the RTEMS Workspace size calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

26.11.7. CONFIGURE_MAXIMUM_POSIX_THREADS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_THREADS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Threads that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

This calculations for the required memory in the RTEMS Workspace for threads assume that each thread has a minimum stack size and has floating point support enabled. The configuration option CONFIGURE_EXTRA_TASK_STACKS is used to specify thread stack requirements above the minimum size required.

The maximum number of Classic API Tasks is specified by CONFIGURE_MAXIMUM_TASKS.

All POSIX threads have floating point enabled.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option shall be small enough so that the task stack space calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

26.11.8. CONFIGURE_MAXIMUM_POSIX_TIMERS

CONSTANT:

CONFIGURE_MAXIMUM_POSIX_TIMERS

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is 0.

DESCRIPTION:

The value of this configuration option defines the maximum number of POSIX API Timers that can be concurrently active.

NOTES:

This object class can be configured in unlimited allocation mode, see Unlimited Objects.

Timers are only available if RTEMS was built with the POSIX API build configuration option enabled.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be greater than or equal to zero.

  • The value of the configuration option shall be less than or equal to 65535.

  • The value of the configuration option shall be less than or equal to a BSP-specific and application-specific value which depends on the size of the memory available to the application.

  • The value of the configuration option may be defined through rtems_resource_unlimited() the enable unlimited objects for the object class, if the value passed to rtems_resource_unlimited() satisfies all other constraints of the configuration option.

  • The value of the configuration option shall be zero if the POSIX API is not enabled (e.g. RTEMS was built without the RTEMS_POSIX_API = True build configuration option). Otherwise a compile time error in the configuration file will occur.

26.11.9. CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE

CONSTANT:

CONFIGURE_MINIMUM_POSIX_THREAD_STACK_SIZE

OPTION TYPE:

This configuration option is an integer define.

DEFAULT VALUE:

The default value is two times the value of CONFIGURE_MINIMUM_TASK_STACK_SIZE.

DESCRIPTION:

The value of this configuration option defines the minimum stack size in bytes for every POSIX thread in the system.

CONSTRAINTS:

The following constraints apply to this configuration option:

  • The value of the configuration option shall be small enough so that the task stack space calculation carried out by <rtems/confdefs.h> does not overflow an integer of type uintptr_t.

  • The value of the configuration option shall be greater than or equal to a BSP-specific and application-specific minimum value.