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| <div class="section" id="address-environments"> |
| <h1>Address Environments<a class="headerlink" href="#address-environments" title="Permalink to this headline">¶</a></h1> |
| <p>CPUs that support memory management units (MMUs) may provide |
| <em>address environments</em> within which tasks and their child threads |
| execute. The configuration indicates the CPUs ability to support |
| address environments by setting the configuration variable |
| <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_HAVE_ADDRENV=y</span></code>. That will enable the selection of |
| the actual address environment support which is indicated by the |
| selection of the configuration variable <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_ADDRENV=y</span></code>. |
| These address environments are created only when tasks are created |
| via <code class="docutils literal notranslate"><span class="pre">exec()</span></code> or <code class="docutils literal notranslate"><span class="pre">exec_module()</span></code> (see |
| <code class="docutils literal notranslate"><span class="pre">include/nuttx/binfmt/binfmt.h</span></code>).</p> |
| <p>When <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_ADDRENV=y</span></code> is set in the board configuration, |
| the CPU-specific logic must provide a set of interfaces as defined |
| in the header file <code class="docutils literal notranslate"><span class="pre">include/nuttx/arch.h</span></code>. These interfaces are |
| listed below and described in detail in the following paragraphs.</p> |
| <p>The CPU-specific logic must provide two categories in interfaces:</p> |
| <ol class="arabic"> |
| <li><p><strong>Binary Loader Support</strong>. These are low-level interfaces used |
| in <code class="docutils literal notranslate"><span class="pre">binfmt/</span></code> to instantiate tasks with address environments. |
| These interfaces all operate on type <code class="docutils literal notranslate"><span class="pre">group_addrenv_t</span></code> which |
| is an abstract representation of a task group’s address |
| environment and the type must be defined in<code class="docutils literal notranslate"><span class="pre">arch/arch.h</span></code> if |
| <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_ADDRENV</span></code> is defined. These low-level interfaces |
| include:</p> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="#c.up_addrenv_create" title="up_addrenv_create"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code></a>: Create an address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_destroy" title="up_addrenv_destroy"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_destroy()</span></code></a>: Destroy an address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_vtext" title="up_addrenv_vtext"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_vtext()</span></code></a>: Returns the virtual base address of the <code class="docutils literal notranslate"><span class="pre">.text</span></code> address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_vdata" title="up_addrenv_vdata"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_vdata()</span></code></a>: Returns the virtual base address of the <code class="docutils literal notranslate"><span class="pre">.bss</span></code>/<code class="docutils literal notranslate"><span class="pre">.data</span></code> address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_heapsize" title="up_addrenv_heapsize"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_heapsize()</span></code></a>: Return the initial heap size.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_select" title="up_addrenv_select"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_select()</span></code></a>: Instantiate an address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_restore" title="up_addrenv_restore"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_restore()</span></code></a>: Restore an address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_clone" title="up_addrenv_clone"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_clone()</span></code></a>: Copy an address environment from one location to another.</p></li> |
| </ul> |
| </li> |
| <li><p><strong>Tasking Support</strong>. Other interfaces must be provided to |
| support higher-level interfaces used by the NuttX tasking |
| logic. These interfaces are used by the functions in <code class="docutils literal notranslate"><span class="pre">sched/</span></code> |
| and all operate on the task group which as been assigned an |
| address environment by <code class="docutils literal notranslate"><span class="pre">up_addrenv_clone()</span></code>.</p> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="#c.up_addrenv_attach" title="up_addrenv_attach"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_attach()</span></code></a>: Clone the group address environment assigned to a new |
| thread. This operation is done when a pthread is created |
| that share’s the same address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_detach" title="up_addrenv_detach"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_detach()</span></code></a>: Release the thread’s reference to a group address |
| environment when a task/thread exits.</p></li> |
| </ul> |
| </li> |
| <li><p><strong>Dynamic Stack Support</strong>. <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_STACK_DYNAMIC=y</span></code> |
| indicates that the user process stack resides in its own |
| address space. This option is also <em>required</em> if |
| <code class="docutils literal notranslate"><span class="pre">CONFIG_BUILD_KERNEL</span></code> and <code class="docutils literal notranslate"><span class="pre">CONFIG_LIBC_EXECFUNCS</span></code> are |
| selected. Why? Because the caller’s stack must be preserved in |
| its own address space when we instantiate the environment of |
| the new process in order to initialize it.</p> |
| <p><strong>NOTE:</strong> The naming of the <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_STACK_DYNAMIC</span></code> |
| selection implies that dynamic stack allocation is supported. |
| Certainly this option must be set if dynamic stack allocation |
| is supported by a platform. But the more general meaning of |
| this configuration environment is simply that the stack has its |
| own address space.</p> |
| <p>If <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_STACK_DYNAMIC=y</span></code> is selected then the |
| platform specific code must export these additional interfaces:</p> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="#c.up_addrenv_ustackalloc" title="up_addrenv_ustackalloc"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_ustackalloc()</span></code></a>: Create a stack address environment</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_ustackfree" title="up_addrenv_ustackfree"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_ustackfree()</span></code></a>: Destroy a stack address environment.</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_vustack" title="up_addrenv_vustack"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_vustack()</span></code></a>: Returns the virtual base address of the stack</p></li> |
| <li><p><a class="reference internal" href="#c.up_addrenv_ustackselect" title="up_addrenv_ustackselect"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_ustackselect()</span></code></a>: Instantiate a stack address environment</p></li> |
| </ul> |
| </li> |
| <li><p>If <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_KERNEL_STACK</span></code> is selected, then each user |
| process will have two stacks: (1) a large (and possibly |
| dynamic) user stack and (2) a smaller kernel stack. However, |
| this option is <em>required</em> if both <code class="docutils literal notranslate"><span class="pre">CONFIG_BUILD_KERNEL</span></code> and |
| <code class="docutils literal notranslate"><span class="pre">CONFIG_LIBC_EXECFUNCS</span></code> are selected. Why? Because when we |
| instantiate and initialize the address environment of the new |
| user process, we will temporarily lose the address environment |
| of the old user process, including its stack contents. The |
| kernel C logic will crash immediately with no valid stack in |
| place.</p> |
| <p>If <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_KERNEL_STACK=y</span></code> is selected then the platform |
| specific code must export these additional interfaces:</p> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="#c.up_addrenv_kstackalloc" title="up_addrenv_kstackalloc"><code class="xref c c-func docutils literal notranslate"><span class="pre">up_addrenv_kstackalloc()</span></code></a>: Allocate the process kernel stack.</p></li> |
| </ul> |
| </li> |
| </ol> |
| <dl class="c function"> |
| <dt id="c.up_addrenv_create"> |
| int <code class="sig-name descname">up_addrenv_create</code><span class="sig-paren">(</span><a class="reference internal" href="../user/structures.html#c.size_t" title="size_t">size_t</a> <em>textsize</em>, <a class="reference internal" href="../user/structures.html#c.size_t" title="size_t">size_t</a> <em>datasize</em>, <a class="reference internal" href="../user/structures.html#c.size_t" title="size_t">size_t</a> <em>heapsize</em>, FAR group_addrenv_t *<em>addrenv</em><span class="sig-paren">)</span>;<a class="headerlink" href="#c.up_addrenv_create" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when a new task is created in order to |
| instantiate an address environment for the new task group. |
| up_addrenv_create() is essentially the allocator of the physical memory for the new task.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>textsize</strong> – The size (in bytes) of the <code class="docutils literal notranslate"><span class="pre">.text</span></code> address |
| environment needed by the task. This region may be read/execute |
| only.</p></li> |
| <li><p><strong>datasize</strong> – The size (in bytes) of the <code class="docutils literal notranslate"><span class="pre">.bss/.data</span></code> address |
| environment needed by the task. This region may be read/write |
| only.</p></li> |
| <li><p><strong>heapsize</strong> – The initial size (in bytes) of the heap address |
| environment needed by the task. This region may be read/write |
| only.</p></li> |
| <li><p><strong>addrenv</strong> – The location to return the representation of the |
| task address environment.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_destroy"> |
| int <code class="sig-name descname">up_addrenv_destroy</code><span class="sig-paren">(</span>group_addrenv_t *<em>addrenv</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_destroy" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when a final thread leaves the task |
| group and the task group is destroyed. This function then destroys |
| the defunct address environment, releasing the underlying physical |
| memory allocated by up_addrenv_create().</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>addrenv</strong> – The representation of the task address environment |
| previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code>.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_vtext"> |
| int <code class="sig-name descname">up_addrenv_vtext</code><span class="sig-paren">(</span>FAR group_addrenv_t <em>addrenv</em>, FAR void **<em>vtext</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_vtext" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>Return the virtual .text address associated with the newly create |
| address environment. This function is used by the binary loaders |
| in order get an address that can be used to initialize the new task.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>addrenv</strong> – The representation of the task address environment |
| previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code>.</p></li> |
| <li><p><strong>vtext</strong> – The location to return the virtual address.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_vdata"> |
| int <code class="sig-name descname">up_addrenv_vdata</code><span class="sig-paren">(</span>FAR group_addrenv_t *<em>addrenv</em>, <a class="reference internal" href="../user/structures.html#c.size_t" title="size_t">size_t</a> <em>textsize</em>, FAR void **<em>vdata</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_vdata" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>Return the virtual .text address associated with the newly create |
| address environment. This function is used by the binary loaders |
| in order get an address that can be used to initialize the new task.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>addrenv</strong> – The representation of the task address environment |
| previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code>.</p></li> |
| <li><p><strong>textsize</strong> – For some implementations, the text and data will |
| be saved in the same memory region (read/write/execute) and, in |
| this case, the virtual address of the data just lies at this |
| offset into the common region.</p></li> |
| <li><p><strong>vdata</strong> – The location to return the virtual address.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_heapsize"> |
| ssize_t <code class="sig-name descname">up_addrenv_heapsize</code><span class="sig-paren">(</span>FAR <em class="property">const</em> group_addrenv_t *<em>addrenv</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_heapsize" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>Return the initial heap allocation size. That is the amount of |
| memory allocated by up_addrenv_create() when the heap memory |
| region was first created. This may or may not differ from the |
| heapsize parameter that was passed to up_addrenv_create().</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>addrenv</strong> – The representation of the task address environment |
| previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code>.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>The initial heap size allocated is returned on success; |
| a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_select"> |
| int <code class="sig-name descname">up_addrenv_select</code><span class="sig-paren">(</span>group_addrenv_t *<em>addrenv</em>, save_addrenv_t *<em>oldenv</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_select" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>After an address environment has been established for a task |
| (via up_addrenv_create()), this function may be called to instantiate |
| that address environment in the virtual address space. This might be |
| necessary, for example, to load the code for the task from a file or |
| to access address environment private data.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>addrenv</strong> – The representation of the task address environment |
| previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_create()</span></code>.</p></li> |
| <li><p><strong>oldenv</strong> – The address environment that was in place before |
| <code class="docutils literal notranslate"><span class="pre">up_addrenv_select()</span></code> was called. This may be used with |
| <code class="docutils literal notranslate"><span class="pre">up_addrenv_restore()</span></code> to restore the original address |
| environment that was in place before <code class="docutils literal notranslate"><span class="pre">up_addrenv_select()</span></code> |
| was called. Note that this may be a task agnostic, |
| platform-specific representation that may or may not be |
| different from <code class="docutils literal notranslate"><span class="pre">group_addrenv_t</span></code>.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_restore"> |
| int <code class="sig-name descname">up_addrenv_restore</code><span class="sig-paren">(</span>save_addrenv_t <em>oldenv</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_restore" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>After an address environment has been temporarily instantiated |
| by up_addrenv_select, this function may be called to restore |
| the original address environment.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>oldenv</strong> – The platform-specific representation of the address |
| environment previously returned by <code class="docutils literal notranslate"><span class="pre">up_addrenv_select()</span></code>.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_clone"> |
| int <code class="sig-name descname">up_addrenv_clone</code><span class="sig-paren">(</span>FAR <em class="property">const</em> task_group_s *<em>src</em>, FAR <em class="property">struct</em> task_group_s *<em>dest</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_clone" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>Duplicate an address environment. This does not copy the underlying |
| memory, only the representation that can be used to instantiate |
| that memory as an address environment.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>src</strong> – The address environment to be copied.</p></li> |
| <li><p><strong>dest</strong> – The location to receive the copied address |
| environment.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_attach"> |
| int <code class="sig-name descname">up_addrenv_attach</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> task_group_s *<em>group</em>, FAR <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_attach" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called from the core scheduler logic when a |
| thread is created that needs to share the address environment |
| of its task group. In this case, the group’s address environment |
| may need to be “cloned” for the child thread.</p> |
| <p>NOTE: In most platforms, nothing will need to be done in this case. |
| Simply being a member of the group that has the address environment |
| may be sufficient.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>group</strong> – The task group to which the new thread belongs.</p></li> |
| <li><p><strong>ctcb</strong> – The TCB of the thread needing the address |
| environment.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_detach"> |
| int <code class="sig-name descname">up_addrenv_detach</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> task_group_s *<em>group</em>, FAR <em class="property">struct</em> task_group_s *<em>tcb</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_detach" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when a task or thread exits in order |
| to release its reference to an address environment. The address |
| environment, however, should persist until up_addrenv_destroy() |
| is called when the task group is itself destroyed. Any resources |
| unique to this thread may be destroyed now.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>group</strong> – The group to which the thread belonged.</p></li> |
| <li><p><strong>tcb</strong> – The TCB of the task or thread whose the address |
| environment will be released.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_ustackalloc"> |
| int <code class="sig-name descname">up_addrenv_ustackalloc</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em>, <a class="reference internal" href="../user/structures.html#c.size_t" title="size_t">size_t</a> <em>stacksize</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_ustackalloc" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when a new thread is created in order |
| to instantiate an address environment for the new thread’s stack. |
| up_addrenv_ustackalloc() is essentially the allocator of the |
| physical memory for the new task’s stack.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread that requires the stack address |
| environment.</p></li> |
| <li><p><strong>stacksize</strong> – The size (in bytes) of the initial stack address |
| environment needed by the task. This region may be read/write |
| only.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_ustackfree"> |
| int <code class="sig-name descname">up_addrenv_ustackfree</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_ustackfree" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when any thread exits. This function then |
| destroys the defunct address environment for the thread’s stack, |
| releasing the underlying physical memory.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread that no longer requires the |
| stack address environment.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_vustack"> |
| int <code class="sig-name descname">up_addrenv_vustack</code><span class="sig-paren">(</span>FAR <em class="property">const</em> <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em>, FAR void **<em>vstack</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_vustack" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>Return the virtual address associated with the newly create stack address environment.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread with the stack address environment of interest.</p></li> |
| <li><p><strong>vstack</strong> – The location to return the stack virtual base address.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_ustackselect"> |
| int <code class="sig-name descname">up_addrenv_ustackselect</code><span class="sig-paren">(</span>FAR <em class="property">const</em> <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_ustackselect" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>After an address environment has been established for a task’s |
| stack (via up_addrenv_ustackalloc(). This function may be called to |
| instantiate that address environment in the virtual address space. |
| This is a necessary step before each context switch to the newly |
| created thread (including the initial thread startup).</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread with the stack address |
| environment to be instantiated.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_kstackalloc"> |
| int <code class="sig-name descname">up_addrenv_kstackalloc</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em><span class="sig-paren">)</span><a class="headerlink" href="#c.up_addrenv_kstackalloc" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when a new thread is created to allocate the |
| new thread’s kernel stack. This function may be called for certain |
| terminating threads which have no kernel stack. It must be |
| tolerant of that case.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread that requires the kernel stack.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt id="c.up_addrenv_kstackfree"> |
| int <code class="sig-name descname">up_addrenv_kstackfree</code><span class="sig-paren">(</span>FAR <em class="property">struct</em> <a class="reference internal" href="../user/structures.html#c.tcb_s" title="tcb_s">tcb_s</a> *<em>tcb</em><span class="sig-paren">)</span>;<a class="headerlink" href="#c.up_addrenv_kstackfree" title="Permalink to this definition">¶</a><br /></dt> |
| <dd><p>This function is called when any thread exits. This function frees the kernel stack.</p> |
| <dl class="field-list simple"> |
| <dt class="field-odd">Parameters</dt> |
| <dd class="field-odd"><ul class="simple"> |
| <li><p><strong>tcb</strong> – The TCB of the thread that no longer requires the |
| kernel stack.</p></li> |
| </ul> |
| </dd> |
| <dt class="field-even">Returns</dt> |
| <dd class="field-even"><p>Zero (OK) on success; a negated errno value on failure.</p> |
| </dd> |
| </dl> |
| </dd></dl> |
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