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Directly use "static inline" which is available in C99 and later. This brings
the RTEMS implementation closer to standard C.
Close #3935.
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Updates #3053.
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If RTEMS_SMP is not defined, then Doxygen adds the comments intended for
conditional the lock member to the next member.
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Use common phrases for the file brief descriptions.
Update #3706.
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In uniprocessor and SMP configurations, the context switch extensions
were called during _Thread_Do_dispatch():
void _Thread_Do_dispatch( Per_CPU_Control *cpu_self, ISR_Level level )
{
Thread_Control *executing;
executing = cpu_self->executing;
...
do {
Thread_Control *heir;
heir = _Thread_Get_heir_and_make_it_executing( cpu_self );
...
_User_extensions_Thread_switch( executing, heir );
...
_Context_Switch( &executing->Registers, &heir->Registers );
...
} while ( cpu_self->dispatch_necessary );
...
}
In uniprocessor configurations, this is fine and the context switch
extensions are called for all thread switches except the very first
thread switch to the initialization thread. However, in SMP
configurations, the context switch may be invalidated and updated in the
low-level _Context_Switch() routine. See:
https://docs.rtems.org/branches/master/c-user/symmetric_multiprocessing_services.html#thread-dispatch-details
In case such an update happens, a thread will execute on the processor
which was not seen in the previous call of the context switch
extensions. This can confuse for example event record consumers which
use events generated by a context switch extension.
Fixing this is not straight forward. The context switch extensions call
must move after the low-level context switch. The problem here is that
we may end up in _Thread_Handler(). Adding the context switch
extensions call to _Thread_Handler() covers now also the thread switch
to the initialization thread. We also have to save the last executing
thread (ancestor) of the processor. Registers or the stack cannot be
used for this purpose. We have to add it to the per-processor
information. Existing extensions may be affected, since now context
switch extensions use the stack of the heir thread. The stack checker
is affected by this.
Calling the thread switch extensions in the low-level context switch is
difficult since at this point an intermediate stack is used which is
only large enough to enable servicing of interrupts.
Update #3885.
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Update #3706.
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The use of a hand crafted lock for Per_CPU_Control::Lock was necessary
at some point in the SMP support development, but it is no longer
justified.
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Update #3706
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Update #3706.
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We have to read the first node again once we obtained the lock since it
may have aready changed.
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Update #3598.
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Update #3598.
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A speciality of the RTEMS build system was the make preinstall step. It
copied header files from arbitrary locations into the build tree. The
header files were included via the -Bsome/build/tree/path GCC command
line option.
This has at least seven problems:
* The make preinstall step itself needs time and disk space.
* Errors in header files show up in the build tree copy. This makes it
hard for editors to open the right file to fix the error.
* There is no clear relationship between source and build tree header
files. This makes an audit of the build process difficult.
* The visibility of all header files in the build tree makes it
difficult to enforce API barriers. For example it is discouraged to
use BSP-specifics in the cpukit.
* An introduction of a new build system is difficult.
* Include paths specified by the -B option are system headers. This
may suppress warnings.
* The parallel build had sporadic failures on some hosts.
This patch removes the make preinstall step. All installed header
files are moved to dedicated include directories in the source tree.
Let @RTEMS_CPU@ be the target architecture, e.g. arm, powerpc, sparc,
etc. Let @RTEMS_BSP_FAMILIY@ be a BSP family base directory, e.g.
erc32, imx, qoriq, etc.
The new cpukit include directories are:
* cpukit/include
* cpukit/score/cpu/@RTEMS_CPU@/include
* cpukit/libnetworking
The new BSP include directories are:
* bsps/include
* bsps/@RTEMS_CPU@/include
* bsps/@RTEMS_CPU@/@RTEMS_BSP_FAMILIY@/include
There are build tree include directories for generated files.
The include directory order favours the most general header file, e.g.
it is not possible to override general header files via the include path
order.
The "bootstrap -p" option was removed. The new "bootstrap -H" option
should be used to regenerate the "headers.am" files.
Update #3254.
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Use forward and reverse order for initial and dynamic extensions. This
is the behaviour documented in the C Users Guide. Change thread
terminate order to backward to be in line with the thread delete order.
Change fatal error order to forward to ensure that initial extensions
are called first due the peculiar execution context of fatal error
extensions, see _Terminate() documentation.
Update #2692.
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The fatal is internal indicator is redundant since the fatal source and
error code uniquely identify a fatal error. Keep the fatal user
extension is internal parameter for backward compatibility and set it to
false always.
Update #2825.
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Use a processor-specific interrupt frame during context switches in case
the executing thread is longer executes on the processor and the heir
thread is about to start execution. During this period we must not use
a thread stack for interrupt processing.
Update #2809.
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Add a lock and use a chain iterator for safe iteration during concurrent
user extension addition and removal.
Ensure that dynamically added thread delete and fatal extensions are
called in reverse order.
Update #2555.
Update #2692.
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Drop the <rtems/score/percpu.h> include since this file exposes a lot of
implementation details.
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The current implementation of task migration in RTEMS has some
implications with respect to the interrupt latency. It is crucial to
preserve the system invariant that a task can execute on at most one
processor in the system at a time. This is accomplished with a boolean
indicator in the task context. The processor architecture specific
low-level task context switch code will mark that a task context is no
longer executing and waits that the heir context stopped execution
before it restores the heir context and resumes execution of the heir
task. So there is one point in time in which a processor is without a
task. This is essential to avoid cyclic dependencies in case multiple
tasks migrate at once. Otherwise some supervising entity is necessary to
prevent life-locks. Such a global supervisor would lead to scalability
problems so this approach is not used. Currently the thread dispatch is
performed with interrupts disabled. So in case the heir task is
currently executing on another processor then this prolongs the time of
disabled interrupts since one processor has to wait for another
processor to make progress.
It is difficult to avoid this issue with the interrupt latency since
interrupts normally store the context of the interrupted task on its
stack. In case a task is marked as not executing we must not use its
task stack to store such an interrupt context. We cannot use the heir
stack before it stopped execution on another processor. So if we enable
interrupts during this transition we have to provide an alternative task
independent stack for this time frame. This issue needs further
investigation.
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The thread deletion is now supported on SMP.
This change fixes the following PRs:
PR1814: SMP race condition between stack free and dispatch
PR2035: psxcancel reveals NULL pointer access in _Thread_queue_Extract()
The POSIX cleanup handler are now called in the right context (should be
called in the context of the terminating thread).
http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_09.html
Add a user extension the reflects a thread termination event. This is
used to reclaim the Newlib reentrancy structure (may use file
operations), the POSIX cleanup handlers and the POSIX key destructors.
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Move implementation specific parts of chain.h and chain.inl into new
header file chainimpl.h. The chain.h contains now only the application
visible API.
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This is the result of a sed script which converts all uses
of @{ into a consistent form.
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This patch is a task from GCI 2012 which improves the Doxygen
comments in the RTEMS source.
http://www.google-melange.com/gci/task/view/google/gci2012/7976215
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The _User_extensions_Thread_switch() function is only used in
_Thread_Dispatch().
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This file contains the parts of <rtems/score/userext.h> that are only
necessary for the RTEMS implementation.
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