17.3. Operations

17.3.1. Creating a Partition

The rtems_partition_create directive creates a partition with a user-specified name. The partition’s name, starting address, length and buffer size are all specified to the rtems_partition_create directive. RTEMS allocates a Partition Control Block (PTCB) from the PTCB free list. This data structure is used by RTEMS to manage the newly created partition. The number of buffers in the partition is calculated based upon the specified partition length and buffer size. If successful,the unique partition ID is returned to the calling task.

17.3.2. Obtaining Partition IDs

When a partition is created, RTEMS generates a unique partition ID and assigned it to the created partition until it is deleted. The partition ID may be obtained by either of two methods. First, as the result of an invocation of the rtems_partition_create directive, the partition ID is stored in a user provided location. Second, the partition ID may be obtained later using the rtems_partition_ident directive. The partition ID is used by other partition manager directives to access this partition.

17.3.3. Acquiring a Buffer

A buffer can be obtained by calling the rtems_partition_get_buffer directive. If a buffer is available, then it is returned immediately with a successful return code. Otherwise, an unsuccessful return code is returned immediately to the caller. Tasks cannot block to wait for a buffer to become available.

17.3.4. Releasing a Buffer

Buffers are returned to a partition’s free buffer chain with the rtems_partition_return_buffer directive. This directive returns an error status code if the returned buffer was not previously allocated from this partition.

17.3.5. Deleting a Partition

The rtems_partition_delete directive allows a partition to be removed and returned to RTEMS. When a partition is deleted, the PTCB for that partition is returned to the PTCB free list. A partition with buffers still allocated cannot be deleted. Any task attempting to do so will be returned an error status code.