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34 <div id="projectname">CMSIS-FreeRTOS
35  <span id="projectnumber">Version 9.1.0</span>
37 <div id="projectbrief">CMSIS-RTOS2 compliant FreeRTOS Implementation</div>
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111 <div class="title">Technical data and limitations </div> </div>
113 <div class="contents">
114 <div class="textblock"><p>This lists the technical data of CMSIS-FreeRTOS.</p>
115 <h1><a class="anchor" id="td_limitations"></a>
117 <p>The following list briefly describes the limitations and unsupported features of the CMSIS-RTOS2 wrapper for FreeRTOS:</p>
119 <li>Static memory allocation will only work if <em>all</em> memory (from attributes structure) is provided statically. In order to allocate object memory statically, you need to:<ul>
120 <li>provide the memory for control blocks and stack in the <code>osThreadAttr_t</code> structure for threads.</li>
121 <li>provide the memory for control blocks and message data in the <code>osMessageQueueAttr_t</code> structure for memory queues.</li>
122 <li>provide the memory for control blocks for other objects in the object's attributes structure.</li>
125 <li>Each timer object requires additional 8 bytes of dynamic memory.</li>
126 <li><code>osKernelSuspend</code> and <code>osKernelResume</code> are not supported.</li>
127 <li><code>osKernelGetTickCount</code> is limited to a 32-bit return value.</li>
128 <li><code>osThreadDetach</code>, <code>osThreadJoin()</code> and attribute <code>osThreadJoinable</code> are not supported (<code>osThreadNew</code> returns NULL when osThreadJoinable attribute is specified).</li>
129 <li><code>osThreadGetStackSize</code> is not implemented.</li>
130 <li>Event flags are limited to 24 bits.</li>
131 <li><code>osEventFlagsGetName</code> is not implemented.</li>
132 <li><code>osEventFlagsWait</code> cannot be called from an ISR.</li>
133 <li>Priority inherit protocol is used as default mutex behavior (<code>osMutexNew</code> creates priority inherit mutex object by default and ignores <code>osMutexPrioInherit</code> attribute when specified).</li>
134 <li>Robust mutex objects are not supported (<code>osMutexNew</code> returns NULL when <code>osMutexRobust</code> attribute is specified).</li>
135 <li><code>osMutexGetName</code> is not implemented and always returns NULL.</li>
136 <li><code>osSemaphoreGetName</code> is not implemented and always returns NULL.</li>
137 <li>Memory Pool functions are not implemented and will always return with error.</li>
138 <li><code>osMessageQueueGetName</code> is not implemented and always returns NULL.</li>
139 <li><code>osMessageQueuePut</code> and <code>osMessageQueueGet</code> always ignore message priority.</li>
141 <h1><a class="anchor" id="td_validation"></a>
142 CMSIS-RTOS validation suite results</h1>
143 <p>CMSIS provides a <a href="http://arm-software.github.io/CMSIS_5/RTOS2/html/rtosValidation.html" target="_blank">validation suite</a> that can be used to test a real-time operating system for compliance to the standard. The test suite has been run successfully on the CMSIS-FreeRTOS implementation with the following exceptions:</p>
144 <p><b>TC_ThreadParam:</b> </p>
146 <li>Reason: unsupported feature</li>
147 <li>Test attempts to test <code>osThreadJoin</code> and <code>osThreadDetach</code> functions for invalid parameter input. These two functions are not implemented.</li>
149 <p><b>TC_ThreadInterrupts:</b> </p>
151 <li>Reason: unsupported feature</li>
152 <li>Test attempts to call <code>osThreadJoin</code> and <code>osThreadDetach</code> from the ISR. These two functions are not implemented.</li>
154 <p><b>TC_EventFlagsInterrupts:</b> </p>
156 <li>Reason: unsupported feature</li>
157 <li>Test attempts to call <code>osEventFlagsWait</code> from the ISR. Wrapper implementation does not allow function <code>osEventFlagsWait</code> to be called from interrupts.</li>
159 <p><b>TC_MutexRobust:</b> </p>
161 <li>Reason: unsupported feature</li>
162 <li>Test attempts to create robust mutex. FreeRTOS implementation does not support robust mutexes.</li>
164 <p><b>TC_MutexOwnership:</b> </p>
166 <li>Reason: unsupported feature</li>
167 <li>Test attempts to release a mutex from a thread which is not the mutex owner. Test fails, because FreeRTOS implementation does not verify ownership on mutex release. </li>
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