Formerly POSIX keys were only enabled when POSIX threads
were enabled. Because they are a truly safe alternative
to per-task variables in an SMP system, they are being
enabled in all configurations.
Change pthread_once from using disabled pre-emption to using a
pthread mutex making it SMP safe. GCC using a posix threading
model uses pthread_once.
The pthread mutex requires at least 1 mutex is configured so
confdefs.h has been updated to account for the internal
mutex.
This patch enables unlimited model in POSIX key manger and have a decent
runtime on POSIX key searching, adding and deleting operations. Memory
overhead is lower than current implementation when the size of key and key
value becomes big.
A common use case for disabled preemption was to ensure mutual exclusion
on single-processor configurations. On SMP this does not work.
To abandon non-preemptible tasks simplifies the scheduler.
Add a configuration field which indicates if the SMP mode of operation
is enabled. This can be used to disable features unsupported on SMP,
e.g task variables.
Delete _Thread_libc_reent and add __getreent() instead according to
__DYNAMIC_REENT__ define.
For SMP configurations __DYNAMIC_REENT__ must be defined.
A Newlib including the following patch is required:
2013-07-09 Sebastian Huber <sebastian.huber@embedded-brains.de>
* libc/include/sys/config.h (__DYNAMIC_REENT__): Define for RTEMS.
The new Simple SMP Scheduler allocates a processor for the processor
count highest priority ready threads. The thread priority and position
in the ready chain are the only information to determine the scheduling
decision. Threads with an allocated processor are in the scheduled
chain. After initialization the scheduled chain has exactly processor
count nodes. Each processor has exactly one allocated thread after
initialization. All enqueue and extract operations may exchange threads
with the scheduled chain. One thread will be added and another will be
removed. The scheduled and ready chain is ordered according to the
thread priority order. The chain insert operations are O(count of ready
threads), thus this scheduler is unsuitable for most real-time
applications.
The thread preempt mode will be ignored.
Delete rtems_configuration_get_smp_maximum_processors(). Delete
rtems_configuration_smp_maximum_processors variable. Add
maximum_processors field to rtems_configuration_table if RTEMS_SMP is
defined. Add rtems_configuration_get_maximum_processors().
Add and use rtems_libio_exit_helper. Add rtems_libio_exit().
The fclose(stdin) etc. makes no sense during exit. This would use the
_REENT structure of the thread calling _exit().
Only one of the following can be defined.
+ CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
+ CONFIGURE_APPLICATION_DOES_NOT_NEED_CLOCK_DRIVER
+ CONFIGURE_APPLICATION_NEEDS_TIMER_DRIVER
Otherwise it is a configuration error which can be detected at
compilation time.
The initial extensions remain now in a read-only table and will not be
copied to work space memory. The extension chains are statically
initialized. This makes it possible to call _User_extensions_Iterate()
independent of the system state. It is now guaranteed that the fatal
callout of the initial extensions will be called provided the stack
pointer, the read-only data, and code memory are valid.
The comment in confdefs.h shows how to do it:
An application can define its own scheduling policy by defining
CONFIGURE_SCHEDULER_USER and the following:
- CONFIGURE_SCHEDULER_ENTRY_POINTS
- CONFIGURE_MEMORY_FOR_SCHEDULER - base memory
- CONFIGURE_MEMORY_PER_TASK_FOR_SCHEDULER - per task memory
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.
Add nanoseconds_per_tick to rtems_configuration_table. This value will
be derived from the microseconds_per_tick value. This avoids some
calculations at run-time.
Read-ahead requests were previously executed in the context of the
reading task. This blocks the reading task until the complete read
with read-ahead transfer is finished. A read-ahead task is introduced
to off-load the read-ahead transfer. This allows the reading task to
work with the requested block more quickly. The read-ahead is triggered
after two misses of ascending consecutive blocks or a read hit of a
block read by the most-recent read-ahead transfer. The read-ahead
feature is configurable and can be disabled.
Script does what is expected and tries to do it as
smartly as possible.
+ remove occurrences of two blank comment lines
next to each other after Id string line removed.
+ remove entire comment blocks which only exited to
contain CVS Ids
+ If the processing left a blank line at the top of
a file, it was removed.
The per file descriptor semaphore (field of rtems_libio_t) is unused in
RTEMS. There is a considerable memory overhead due to that. A
semaphore needs roughly 124 bytes which is huge compared to the
approximately 72 bytes for the file descriptor structure itself. Device
drivers can create their own synchronization primitives in the open
handler on demand.
New macros
o _Objects_Maximum_per_allocation(),
o rtems_resource_is_unlimited(), and
o rtems_resource_maximum_per_allocation().
New function
o _Objects_Is_unlimited().
Adds to confdefs a way to specify rtems_resource_unlimited for classic and
posix objects using a new macro CONFIGURE_OBJECTS_UNLIMITED.
Use CONFIGURE_OBJECTS_ALLOCATION_SIZE to declare the allocation size for
extending the set of objects at runtime. Updates the unlimited sample
to demonstrate how to use the new macros. Also adds new documentation in
the C User's Manual regarding configuring with unlimited objects.
o A new data structure rtems_filesystem_global_location_t was
introduced to be used for
o the mount point location in the mount table entry,
o the file system root location in the mount table entry,
o the root directory location in the user environment, and
o the current directory location in the user environment.
During the path evaluation global start locations are obtained to
ensure that the current file system instance will be not unmounted in
the meantime.
o The user environment uses now reference counting and is protected
from concurrent access.
o The path evaluation process was completely rewritten and simplified.
The IMFS, RFS, NFS, and DOSFS use now a generic path evaluation
method. Recursive calls in the path evaluation have been replaced
with iteration to avoid stack overflows. Only the evaluation of
symbolic links is recursive. No dynamic memory allocations and
intermediate buffers are used in the high level path evaluation. No
global locks are held during the file system instance specific path
evaluation process.
o Recursive symbolic link evaluation is now limited by
RTEMS_FILESYSTEM_SYMLOOP_MAX. Applications can retrieve this value
via sysconf().
o The device file system (devFS) uses now no global variables and
allocation from the workspace. Node names are allocated from the
heap.
o The upper layer lseek() performs now some parameter checks.
o The upper layer ftruncate() performs now some parameter checks.
o unmask() is now restricted to the RWX flags and protected from
concurrent access.
o The fchmod_h and rmnod_h file system node handlers are now a file
system operation.
o The unlink_h operation has been removed. All nodes are now destroyed
with the rmnod_h operation.
o New lock_h, unlock_h, clonenod_h, and are_nodes_equal_h file system
operations.
o The path evaluation and file system operations are now protected by
per file system instance lock and unlock operations.
o Fix and test file descriptor duplicate in fcntl().
o New test fstests/fsnofs01.
PR 1924/cpukit
* sapi/include/rtems/config.h: Added stack_allocate_init_hook to
rtems_configuration_table.
* sapi/include/confdefs.h: Added CONFIGURE_TASK_STACK_FROM_ALLOCATOR
and CONFIGURE_TASK_STACK_ALLOCATOR_INIT defines. Set default stack
allocator and free hook to _Workspace_Allocate() and _Workspace_Free()
respectively.
* score/src/thread.c, score/src/threadstackallocate.c,
score/src/threadstackfree.c: Update due to API changes.
PR 1924/cpukit
* sapi/include/rtems/config.h: New fields stack_space_size,
unified_work_area, and stack_allocator_avoids_work_space in
rtems_configuration_table.
* sapi/include/confdefs.h: Removed rtems_unified_work_area (this is
now part of the Configuration). Separate work space and stack space
estimate. Added CONFIGURE_TASK_STACK_ALLOCATOR_AVOIDS_WORK_SPACE
configuration option.
* libmisc/shell/main_wkspaceinfo.c, score/src/wkspace.c,
libcsupport/src/malloc_initialize.c: Update due to API changes.
PR 1906/cpukit
* sapi/Makefile.am, sapi/preinstall.am, sapi/include/confdefs.h,
score/Makefile.am, score/preinstall.am: Add the CBS (Constant
Bandwidth Server) scheduler. This is a complex scheduling policy
built atop of the EDF scheduler. Unlike other schedulers, this one
provides a user API and handles not only deadlines of tasks but also
claimed budget per period. The main aim of the scheduler is isolation
of tasks so that each task is guaranteed to meet all deadlines
regardless of how other tasks behave.
* sapi/include/rtems/cbs.h, sapi/inline/rtems/cbs.inl,
score/include/rtems/score/schedulercbs.h, score/src/schedulercbs.c,
score/src/schedulercbsattachthread.c,
score/src/schedulercbscleanup.c,
score/src/schedulercbscreateserver.c,
score/src/schedulercbsdestroyserver.c,
score/src/schedulercbsdetachthread.c,
score/src/schedulercbsgetapprovedbudget.c,
score/src/schedulercbsgetexecutiontime.c,
score/src/schedulercbsgetparameters.c,
score/src/schedulercbsgetremainingbudget.c,
score/src/schedulercbsgetserverid.c,
score/src/schedulercbsreleasejob.c,
score/src/schedulercbssetparameters.c,
score/src/schedulercbsunblock.c: New files.
