Ensure that the global construction is performed in the context of the
first initialization thread. On SMP this was not guaranteed in the
previous implementation.
A resource is something that has at most one owner at a time and may
have multiple rivals in case an owner is present. The owner and rivals
are impersonated via resource nodes. A resource is represented via the
resource control structure. The resource controls and nodes are
organized as trees. It is possible to detect deadlocks via such a
resource tree. The _Resource_Iterate() function can be used to iterate
through such a resource tree starting at a top node.
Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).
The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J. Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013. It is a
generalization of the Priority Ceiling Protocol to SMP systems. Each
MrsP semaphore uses a ceiling priority per scheduler instance. These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object. Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily. In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.
The help out feature is not implemented with this patch.
The function to change a thread priority was too complex. Simplify it
with a new scheduler operation. This increases the average case
performance due to the simplified logic. The interrupt disabled
critical section is a bit prolonged since now the extract, update and
enqueue steps are executed atomically. This should however not impact
the worst-case interrupt latency since at least for the Deterministic
Priority Scheduler this sequence can be carried out with a wee bit of
instructions and no loops.
Add _Scheduler_Change_priority() to replace the sequence of
- _Thread_Set_transient(),
- _Scheduler_Extract(),
- _Scheduler_Enqueue(), and
- _Scheduler_Enqueue_first().
Delete STATES_TRANSIENT, _States_Is_transient() and
_Thread_Set_transient() since this state is now superfluous.
With this change it is possible to get rid of the
SCHEDULER_SMP_NODE_IN_THE_AIR state. This considerably simplifies the
implementation of the new SMP locking protocols.
Per task variables are inherently unsafe in SMP systems. This
patch disables them from the build and adds warnings in the
appropriate documentation and configuration sections.
Issue a fatal error in case a thread is deleted which still owns
resources (e.g. a binary semaphore with priority inheritance or ceiling
protocol). The resource count must be checked quite late since RTEMS
task variable destructors, POSIX key destructors, POSIX cleanup handler,
the Newlib thread termination extension or other thread termination
extensions may release resources. In this context it would be quite
difficult to return an error status to the caller.
An alternative would be to place threads with a non-zero resource count
not on the zombie chain. Thus we have a resource leak instead of a
fatal error. The terminator thread can see this error if we return an
RTEMS_RESOURCE_IN_USE status for the rtems_task_delete() for example.
Split sp09 screen 1 into new test sptask_err04.
Split sp09 screen 2 into new tests sptask__err02 and spclock_err01,
as well as moving one verification into sptimer_err01.
Add a CPU counter interface to allow access to a free-running counter.
It is useful to measure short time intervals. This can be used for
example to enable profiling of critical low-level functions.
Add two busy wait functions rtems_counter_delay_ticks() and
rtems_counter_delay_nanoseconds() implemented via the CPU counter.
This adds five tests for <sys/cpuset.h>. It does not include
tests for CPU_XXX_S methods. The autotools should be able to
avoid enabling the tests unless the toolset has <sys/cpuset.h>.
Add CPU port type CPU_Exception_frame and function
_CPU_Exception_frame_print().
The CPU ports of avr, bfin, h8300, lm32, m32c, m32r, m68k, nios2, sh,
sparc64, and v850 use an empty default implementation of
_CPU_Exception_frame_print().
Add rtems_exception_frame and rtems_exception_frame_print().
Add RTEMS_FATAL_SOURCE_EXCEPTION for CPU exceptions. Use rtems_fatal()
with source RTEMS_FATAL_SOURCE_EXCEPTION in CPU ports of i386, powerpc,
and sparc for unexpected exceptions.
Add third parameter to RTEMS_BSP_CLEANUP_OPTIONS() which controls the
BSP_PRINT_EXCEPTION_CONTEXT define used in the default
bsp_fatal_extension().
Add test sptests/spfatal26.
System events are similar to normal events. They offer a second set of
events. These events are intended for internal RTEMS use and should not
be used by applications (with the exception of the transient system
event).
The work areas (RTEMS work space and C program heap) will be initialized
now in a separate step and are no longer part of
rtems_initialize_data_structures(). Initialization is performed with
tables of Heap_Area entries. This allows usage of scattered memory
areas present on various small scale micro-controllers.
The sbrk() support API changes also. The bsp_sbrk_init() must now deal
with a minimum size for the first memory chunk to take the configured
work space size into account.
The changes in _Thread_Dispatch() of commits
dad36c52b8 and
d4dc7c8196 introduced a severe bug which
destroys the real-time properties of RTEMS completely.
Consider the following scenario. We have three tasks L (lowest
priority), M (middle priority), and H (highest priority). Now let a
thread dispatch from M to L happen. An interrupt occurs in
_Thread_Dispatch() here:
void _Thread_Dispatch( void )
{
[...]
post_switch:
_ISR_Enable( level );
<-- INTERRUPT
<-- AFTER INTERRUPT
_Thread_Unnest_dispatch();
_API_extensions_Run_postswitch();
}
The interrupt event makes task H ready. The interrupt code will see
_Thread_Dispatch_disable_level > 0 and thus doesn't perform a
_Thread_Dispatch(). Now we return to position "AFTER INTERRUPT". This
means task L executes now although task H is ready! Task H will execute
once someone calls _Thread_Dispatch().
