From e88d94ffdc7cede81da4da9d87c8f89fdd02db64 Mon Sep 17 00:00:00 2001
From: patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3>
Date: Tue, 18 Dec 2012 16:15:27 +0000
Subject: [PATCH] Restructre address environment interfaces in preparation for
 incorporation into binfmt/ logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5442 42af7a65-404d-4744-a932-0658087f49c3
---
 Documentation/NuttXBinfmt.html       |  14 +-
 Documentation/NuttxPortingGuide.html | 259 ++++++++++++++++++++++--
 arch/z80/include/z180/arch.h         |  23 +++
 arch/z80/src/z180/z180_mmu.c         | 283 +++++++++++++++++++--------
 include/nuttx/arch.h                 | 194 +++++++++++++-----
 include/nuttx/binfmt/binfmt.h        |   4 +-
 6 files changed, 624 insertions(+), 153 deletions(-)

diff --git a/Documentation/NuttXBinfmt.html b/Documentation/NuttXBinfmt.html
index 830a05caa3c..9c9fd3a510b 100644
--- a/Documentation/NuttXBinfmt.html
+++ b/Documentation/NuttXBinfmt.html
@@ -164,13 +164,13 @@ struct binary_s
 };
 </pre></ul>
 
-<ul><p><small>
-  <sup>1</sup>The <code>filename</code> must be the full, absolute path to the file to be executed unless <code>CONFIG_BINFMT_EXEPATH</code> is defined.
-  In that case, <code>filename</code> may be a relative path;
-  a set of candidate absolute paths will be generated using the <code>PATH</code> environment variable and <a href="#load_module"><code>load_module()</code></a> will attempt to load each file that is found at those absolute paths.
-</small></p></ul>
-
-</p>
+<ul>
+  <p><small>
+    <sup>1</sup>The <code>filename</code> must be the full, absolute path to the file to be executed unless <code>CONFIG_BINFMT_EXEPATH</code> is defined.
+    In that case, <code>filename</code> may be a relative path;
+    a set of candidate absolute paths will be generated using the <code>PATH</code> environment variable and <a href="#load_module"><code>load_module()</code></a> will attempt to load each file that is found at those absolute paths.
+  </small></p>
+</ul>
 
 <p>
   Where the types <code>binfmt_ctor_t</code> and <code>binfmt_dtor_t</code> define the type of one C++ constructor or destructor:
diff --git a/Documentation/NuttxPortingGuide.html b/Documentation/NuttxPortingGuide.html
index 5361a28665e..526892d3ef9 100644
--- a/Documentation/NuttxPortingGuide.html
+++ b/Documentation/NuttxPortingGuide.html
@@ -12,7 +12,7 @@
       <h1><big><font color="#3c34ec">
         <i>NuttX RTOS Porting Guide</i>
       </font></big></h1>
-      <p>Last Updated: December 17, 2012</p>
+      <p>Last Updated: December 18, 2012</p>
     </td>
   </tr>
 </table>
@@ -92,7 +92,8 @@
       <a href="#upenableirq">4.1.17 <code>up_enable_irq()</code></a><br>
       <a href="#upprioritizeirq">4.1.18 <code>up_prioritize_irq()</code></a></br>
       <a href="#upputc">4.1.19 <code>up_putc()</code></a></br>
-      <a href="#systemtime">4.1.20 System Time and Clock</a>
+      <a href="#systemtime">4.1.20 System Time and Clock</a><br>
+      <a href="#addrenv">4.1.21 Address Environments</a>
     </ul>
     <a href="#exports">4.2 APIs Exported by NuttX to Architecture-Specific Logic</a>
     <ul>
@@ -1622,7 +1623,7 @@ The system can be re-made subsequently by just typing <code>make</code>.
   is defined.
 </p>
 
-<p><b>Inputs</b>:</p>
+<p><b>Input Parameters</b>:</p>
 <ul>
   <li>
     <code>tcb</code>: The TCB of new task.
@@ -1658,7 +1659,7 @@ The system can be re-made subsequently by just typing <code>make</code>.
   is defined.
 </p>
 
-<p><b>Inputs:</b></p>
+<p><b>Input Parameters:</b></p>
 <ul>
   <li>
     <code>tcb</code>: The TCB of new task.
@@ -1694,7 +1695,7 @@ The system can be re-made subsequently by just typing <code>make</code>.
   function is called.
 </p>
 
-<p><b>Inputs</b>:
+<p><b>Input Parameters</b>:
 <ul>
   <li><code>tcb</code>: Refers to the tcb to be unblocked.  This tcb is
     in one of the waiting tasks lists.  It must be moved to
@@ -1715,7 +1716,7 @@ The system can be re-made subsequently by just typing <code>make</code>.
   logic.  Interrupts will always be disabled when this
   function is called.
 
-<p><b>Inputs:</b></p>
+<p><b>Input Parameters:</b></p>
 <ul>
   <li><code>tcb</code>: Refers to a task in the ready-to-run list (normally
     the task at the head of the list).  It most be
@@ -1771,7 +1772,7 @@ The system can be re-made subsequently by just typing <code>make</code>.
   function is called.
 </p>
 
-<p><b>Inputs:</b></p>
+<p><b>Input Parameters:</b></p>
 <ul>
   <li>
     <code>tcb</code>: The TCB of the task that has been reprioritized
@@ -2110,6 +2111,236 @@ else
   To retrieve that variable use:
 </p>
 
+<h3><a name="addrenv">4.1.21 Address Environments</a></h3>
+
+<p>
+  CPUs that support memory management units (MMUs) may provide <i>address environments</i> within which tasks and their child threads execute.
+  The configuration indicates the CPUs ability to support address environments by setting the configuration varabile <code>CONFIG_ADDRENV=y</code>.
+  These address environments are created only when tasks are created via <code>exec()</code> or <code>exec_module()</code> (see <code>include/nuttx/binfmt/binfmt.h</code>).
+</p>
+<p>
+  When <code>CONFIG_ADDRENV=y</code> is set in the board configuration, the CPU-specific logic must provide a set of interfaces as defined in the header file <code>include/nuttx/arch.h</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>
+  <li>
+    <p>
+      <b>Binary Loader Support</b>.
+      These are low-level interfaces used in <code>binfmt/</code> to instantiate tasks with address environments.
+      These interfaces all operate on type <code>task_addrenv_t</code> which is an abstract representation of a asks's address environment and must be defined in arch/arch.h if <code>CONFIG_ADDRENVM</code> is defined.
+      These low-level interfaces include:
+    </p>
+    <ul>
+      <li>
+        <a href="#up_addrenv_create">4.1.21.1 <code>up_addrenv_create()</code></a>:
+        Create an address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_vaddr">4.1.21.2 <code>up_addrenv_vaddr()</code></a>:
+        Returns the virtual base address of the address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_select">4.1.21.3 <code>up_addrenv_select()</code></a>: 
+        Instantiate an address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_restore">4.1.21.4 <code>up_addrenv_restore()</code></a>: 
+        Restore an address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_destroy">4.1.21.5 <code>up_addrenv_destroy()</code></a>:
+        Destroy an address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_assign">4.1.21.6 <code>up_addrenv_assign()</code></a>:
+        Assign an address environment to a TCB.
+      </li>
+    </ul>
+  </li>
+  <li>
+    <p>
+      <b>Tasking Support</b>.
+      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>sched/</code> and all operate on the TCB which as been assigned an address environment by <code>up_addrenv_assign()</code>.
+    </p>
+    <ul>
+      <li>
+        <a href="#up_addrenv_share">4.1.21.7 <code>up_addrenv_share()</code></a>:
+        Clone the address environment assigned to one TCB to another.
+        This operation is done when a pthread is created that share's the same address environment.
+      </li>
+      <li>
+        <a href="#up_addrenv_release">4.1.21.8 <code>up_addrenv_release()</code></a>:
+        ARelease the TCBs reference to an address environment when a task/thread exits.
+      </li>
+    </ul>
+  </li>
+</ol>
+
+
+<h4><a name="up_addrenv_create">4.1.21.1 <code>up_addrenv_create()</code></a></h4>
+<p><b>Prototype</b>:</p>
+<ul>
+  <code>int up_addrenv_create(size_t envsize, FAR task_addrenv_t *addrenv);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  This function is called from the binary loader logic when a new task is created in order to instantiate an address environment for the task.
+  <code>up_addrenv_create()</code> is essentially the allocator of the physical memory for the new task.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>envsize</code>: The size (in bytes) of the address environment needed by the task.</li>
+  <li><code>addrenv</code>: The location to return the representation of the task address environment.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_vaddr">4.1.21.2 <code>up_addrenv_vaddr()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_vaddr(FAR task_addrenv_t addrenv, FAR void **vaddr);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  Return the virtual 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.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>addrenv</code>: The representation of the task address environment previously returned by up_addrenv_create.</li>
+  <li><code>vaddr</code>: The location to return the virtual address.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_select">4.1.21.3 <code>up_addrenv_select()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_select(task_addrenv_t addrenv, hw_addrenv_t *oldenv);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  After an address environment has been established for a task (via <code>up_addrenv_create())</code>, this function may be called to 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.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>addrenv</code>: The representation of the task address environment previously returned by up_addrenv_create.</li>
+  <li><code>oldenv</code>:
+    The address environment that was in place before <code>up_addrenv_select()</code> was called.
+    This may be used with <code>up_addrenv_restore()</code> to restore the original  address environment that was in place before <code>up_addrenv_select()</code> was called.
+    Note that this may be a task agnostic, hardware representation that is different from <code>task_addrenv_t</code>.
+  </li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_restore">4.1.21.4 <code>up_addrenv_restore()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_restore(hw_addrenv_t oldenv);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  After an address environment has been temporarilty instantiated by <code>up_addrenv_select</code>,
+  this function may be called to to restore the original address environment.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>oldenv</code>: The hardware representation of the address environment previously returned by <code>up_addrenv_select()</code>.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_destroy">4.1.21.5 <code>up_addrenv_destroy()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_destroy(task_addrenv_t addrenv);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  Called from the binary loader loader during error handling to destroy the address environment previously created by <code>up_addrenv_create()</code>.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>addrenv</code>: The representation of the task address environment previously returned by up_addrenv_create.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_assign">4.1.21.6 <code>up_addrenv_assign()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_assign(task_addrenv_t addrenv, FAR _TCB *tcb);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  Assign an address environment to a TCB.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>addrenv</code>: The representation of the task address environment previously returned by up_addrenv_create.</li>
+  <li><code>tcb</code>: The TCB of the task to receive the address environment.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_share">4.1.21.7 <code>up_addrenv_share()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_share(FAR const _TCB *ptcb, FAR _TCB *ctcb);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  This function is called from the core scheduler logic when a thread is created that needs to share the address ennvironment of its parent task.
+  In this case, the parent's address environment needs to be &quot;cloned&quot; for the child thread.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>ptcb</code>: The TCB of the parent task that has the address environment.</li>
+  <li><code>ctcb</code>: The TCB of the child thread needing the address environment.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
+<h4><a name="up_addrenv_release">4.1.21.8 <code>up_addrenv_release()</code></a></h4>
+<p><b>Prototype</b>:<p>
+<ul>
+  <code>int up_addrenv_release(FAR _TCB *tcb);</code>
+</ul>
+<p><b>Description</b>:</p>
+<ul>
+  This function is called when a task or thread exits in order to release its reference to an address environment.
+  When there are no furtherreferences to an address environment, that address environment should
+  be destroyed.
+</ul>
+<p><b>Input Parameters</b>:</p>
+<ul>
+  <li><code>tcb</code>: The TCB of the task or thread whose the address environment will be released.</li>
+</ul>
+<p><b>Returned Value</b>:</p>
+<ul>
+  Zero (<code>OK</code>) on success; a negated <code>errno</code> value on failure.
+</ul>
+
 <h2><a name="exports">4.2 APIs Exported by NuttX to Architecture-Specific Logic</a></h2>
 <p>
   These are standard interfaces that are exported by the OS
@@ -3470,7 +3701,7 @@ extern void up_ledoff(int led);
   All PM interfaces are declared in the file <code>include/nuttx/power/pm.h</code>.
 </p>
 
-<h4><a name="pminitialize">6.4.2.1 pm_initialize()</a></h4>
+<h4><a name="pminitialize">6.4.2.1 <code>pm_initialize()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
@@ -3487,7 +3718,7 @@ None
 None
 </p>
 
-<h4><a name="pmregister">6.4.2.2 pm_register()</a></h4>
+<h4><a name="pmregister">6.4.2.2 <code>pm_register()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
@@ -3507,7 +3738,7 @@ int pm_register(FAR struct pm_callback_s *callbacks);
 Zero (<code>OK</code>) on success; otherwise a negater <code>errno</code> value is returned.
 </p>
 
-<h4><a name="pmactivity">6.4.2.3 pm_activity()</a></h4>
+<h4><a name="pmactivity">6.4.2.3 <code>pm_activity()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
@@ -3534,7 +3765,7 @@ void pm_activity(int priority);
   This function may be called from an interrupt handler (this is the ONLY PM function that may be called from an interrupt handler!).
 </p>
 
-<h4><a name="pmcheckstate">6.4.2.4 pm_checkstate()</a></h4>
+<h4><a name="pmcheckstate">6.4.2.4 <code>pm_checkstate()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
@@ -3561,7 +3792,7 @@ enum pm_state_e pm_checkstate(void);
   The recommended power management state.
 </p>
 
-<h4><a name="pmchangestate">6.4.2.5 pm_changestate()</a></h4>
+<h4><a name="pmchangestate">6.4.2.5 <code>pm_changestate()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
@@ -3596,7 +3827,7 @@ enum pm_state_e pm_checkstate(void);
   These callback functions can be used to provide power management information to the driver.
 </p>
 
-<h4><a name="pmprepare">6.4.3.1 prepare()</a></h4>
+<h4><a name="pmprepare">6.4.3.1 <code>prepare()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 int (*prepare)(FAR struct pm_callback_s *cb, enum pm_state_e pmstate);
@@ -3624,7 +3855,7 @@ int (*prepare)(FAR struct pm_callback_s *cb, enum pm_state_e pmstate);
    consumption modes!
 </p>
 
-<h4><a name="pmnotify">6.4.3.1 notify()</a></h4>
+<h4><a name="pmnotify">6.4.3.1 <code>notify()</code></a></h4>
 <p><b>Function Prototype:</b></p>
 <ul><pre>
 #include &lt;nuttx/power/pm.h&gt;
diff --git a/arch/z80/include/z180/arch.h b/arch/z80/include/z180/arch.h
index 9e219752223..d7cf82a268d 100644
--- a/arch/z80/include/z180/arch.h
+++ b/arch/z80/include/z180/arch.h
@@ -45,6 +45,12 @@
  * Included Files
  ****************************************************************************/
 
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+#include <arch/irq.h>
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -52,6 +58,23 @@
 /****************************************************************************
  * Public Types
  ****************************************************************************/
+/* The z180 address environment is represented in hardware as the 8-bit
+ * Common Base Register (CBR).  CBR specifies the base address (on 4KB
+ * boundaries) used to generate a 20-bit physical address for Common Area 1
+ * accesses.  CBR is the upper 8-bits of the 20-bit address; the lower 14-bits
+ * of the base address are implicitly zero (hence the 4KB boundary alignment).
+ */
+
+#ifdef CONFIG_ADDRENV
+typedef uint8_t hw_addrenv_t;
+
+/* At the task-level, the z180 address environment is represented as struct
+ * z180_cbr_s which is defined in irq.h.
+ */
+
+struct z180_cbr_s;
+typedef FAR struct z180_cbr_s *task_addrenv_t;
+#endif
 
 /****************************************************************************
  * Public Variables
diff --git a/arch/z80/src/z180/z180_mmu.c b/arch/z80/src/z180/z180_mmu.c
index e24b22b8e1a..5f9b26be2bf 100644
--- a/arch/z80/src/z180/z180_mmu.c
+++ b/arch/z80/src/z180/z180_mmu.c
@@ -79,7 +79,7 @@ static struct z180_cbr_s g_cbrs[CONFIG_MAX_TASKS];
  ****************************************************************************/
 
 /****************************************************************************
- * Name: z180_mmu_findcbr
+ * Name: z180_mmu_alloccbr
  *
  * Description:
  *   Find an unused struture in g_cbrs (i.e., one with reference count == 0).
@@ -88,7 +88,7 @@ static struct z180_cbr_s g_cbrs[CONFIG_MAX_TASKS];
  *
  ****************************************************************************/
 
-static FAR struct z180_cbr_s *z180_mmu_findcbr(void)
+static inline FAR struct z180_cbr_s *z180_mmu_alloccbr(void)
 {
   int i;
 
@@ -176,25 +176,54 @@ return g_physhandle ? OK : -ENOMEM;
 #endif
 }
 
+/****************************************************************************
+ * Address Environment Interfaces
+ *
+ * Low-level interfaces used in binfmt/ to instantiate tasks with address
+ * environments.  These interfaces all operate on task_addrenv_t which is an
+ * abstract representation of the address environment and must be provided
+ * by arch/arch.h is CONFIG_ADDRENV is defined.
+ *
+ *   up_addrenv_create  - Create an address environment
+ *   up_addrenv_vaddr   - Returns the virtual base address of the address
+ *                        environment
+ *   up_addrenv_select  - Instantiate an address environment
+ *   up_addrenv_destroy - Destroy an address environment.
+ *   up_addrenv_assign  - Assign an address environment to a TCB
+ *
+ * Higher-level interfaces used by the tasking logic.  These interfaces are
+ * used by the functions in sched/ and all operate on the TCB which as been
+ * assigned an address environment by up_addrenv_assign().
+ *
+ *   up_addrenv_share   - Clone the address environment assigned to one TCB
+ *                        to another.  This operation is done when a pthread
+ *                        is created that share's the same address
+ *                        environment.
+ *   up_addrenv_release - Release the TCBs reference to an address
+ *                        environment when a task/thread exists.
+ *
+ ****************************************************************************/
 /****************************************************************************
  * Name: up_addrenv_create
  *
  * Description:
  *   This function is called from the binary loader logic when a new
- *   task is created in RAM in order to instantiate an address environment for
- *   the task.
+ *   task is created in order to instantiate an address environment for the
+ *   task.  up_addrenv_create is essentially the allocator of the physical
+ *   memory for the new task.
  *
  * Input Parameters:
- *   tcb - The TCB of the task needing the address environment.
  *   envsize - The size (in bytes) of the address environment needed by the
  *     task.
+ *   addrenv - The location to return the representation of the task address
+ *     environment.
  *
  * Returned Value:
  *   Zero (OK) on success; a negated errno value on failure.
  *
  ****************************************************************************/
 
-int up_addrenv_create(FAR _TCB *tcb, size_t envsize)
+int up_addrenv_create(size_t envsize, FAR task_addrenv_t *addrenv)
 {
   FAR struct z180_cbr_s *cbr;
   irqstate_t flags;
@@ -202,10 +231,6 @@ int up_addrenv_create(FAR _TCB *tcb, size_t envsize)
   unsigned int npages;
   int ret;
 
-  /* Make sure that there is no address environment in place on this TCB */
-
-  DEBUGASSERT(tcb->xcp.cbr == NULL);
-
   /* Convert the size from bytes to numbers of pages */
 
   npages = PHYS_ALIGNUP(envsize);
@@ -225,7 +250,7 @@ int up_addrenv_create(FAR _TCB *tcb, size_t envsize)
    */
 
   flags = irqsave();
-  cbr = z180_mmu_findcbr();
+  cbr = z180_mmu_alloccbr();
   if (!cbr)
     {
       sdbg("ERROR: No free CBR structures\n");
@@ -235,7 +260,6 @@ int up_addrenv_create(FAR _TCB *tcb, size_t envsize)
 
   /* Now allocate the physical memory to back up the address environment */
 
-
 #ifdef CONFIG_GRAN_SINGLE
   alloc = (uintptr_t)gran_alloc(npages);
 #else
@@ -254,9 +278,9 @@ int up_addrenv_create(FAR _TCB *tcb, size_t envsize)
 
   DEBUGASSERT(alloc <= 0xff);
 
-  cbr->cbr     = alloc;
-  cbr->pages   = npages;
-  tcb->xcp.cbr = cbr;
+  cbr->cbr     = (uint8_t)alloc;
+  cbr->pages   = (uint8_t)npages;
+  *addrenv     = (task_addrenv_t)cbr;
 
   irqrestore(flags);
   return OK;
@@ -269,6 +293,165 @@ errout_with_irq:
   return ret;
 }
 
+/****************************************************************************
+ * Name: up_addrenv_vaddr
+ *
+ * Description:
+ *   Return the virtual 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..
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *      returned by up_addrenv_create.
+ *   vaddr - The location to return the virtual address.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int up_addrenv_vaddr(FAR task_addrenv_t addrenv, FAR void **vaddr)
+{
+  return CONFIG_Z180_COMMON1AREA_VIRTBASE;
+}
+
+/****************************************************************************
+ * Name: up_addrenv_select
+ *
+ * Description:
+ *   After an address environment has been established for a task (via
+ *   up_addrenv_create()), this function may be called to 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.
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *   oldenv
+ *     The address environment that was in place before up_addrenv_select().
+ *     This may be used with up_addrenv_restore() to restore the original
+ *     address environment that was in place before up_addrenv_select() was
+ *     called.  Note that this may be a task agnostic, hardware
+ *     representation that is different from task_addrenv_t.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int up_addrenv_select(task_addrenv_t addrenv, hw_addrenv_t *oldenv)
+{
+  FAR struct z180_cbr_s *cbr = (FAR struct z180_cbr_s *)addrenv;
+  irqstate_t flags;
+
+  DEBUGASSERT(cbr && oldenv);
+
+  /* Return the current CBR value from the CBR register */
+
+  flags = irqsave();
+  *oldenv = (hw_addrenv_t)inp(Z180_MMU_CBR);
+
+  /* Write the new CBR value into CBR register */
+
+  outp(Z180_MMU_CBR, cbr->cbr);
+  irqrestore(flags);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_addrenv_restore
+ *
+ * Description:
+ *   After an address environment has been temporarilty instantiated by
+ *   up_addrenv_select, this function may be called to to restore the
+ *   original address environment.
+ *
+ * Input Parameters:
+ *   oldenv - The hardware representation of the address environment
+ *     previously returned by up_addrenv_select.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int up_addrenv_restore(hw_addrenv_t oldenv)
+{
+  outp(Z180_MMU_CBR, (uint8_t)oldenv);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_addrenv_destroy
+ *
+ * Description:
+ *   Called from the binary loader loader during error handling to destroy
+ *   the address environment previously created by up_addrenv_create().
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int up_addrenv_destroy(task_addrenv_t addrenv)
+{
+  FAR struct z180_cbr_s *cbr = (FAR struct z180_cbr_s *)addrenv;
+
+  DEBUGASSERT(cbr);
+
+  /* Free the physical address space backing up the mapping */
+
+#ifdef CONFIG_GRAN_SINGLE
+  gran_free((FAR void *)cbr->cbr, cbr->pages);
+#else
+  gran_free(g_physhandle, (FAR void *)cbr->cbr, cbr->pages);
+#endif
+
+  /* And make the CBR structure available for re-use */
+
+  z180_mmu_freecbr(cbr);
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_addrenv_assign
+ *
+ * Description:
+ *   Assign an address environment to a TCB.
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *   tcb - The TCB of the task to receive the address environment.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+int up_addrenv_assign(task_addrenv_t addrenv, FAR _TCB *tcb)
+{
+  FAR struct z180_cbr_s *cbr = (FAR struct z180_cbr_s *)addrenv;
+  int ret;
+
+  /* Make sure that there is no address environment in place on this TCB */
+
+  DEBUGASSERT(cbr && tcb->xcp.cbr == NULL);
+
+  /* Save the CBR strucure in the TCB.  This is an atomic operation so no
+   * special precautions should be needed.
+   */
+
+  tcb->xcp.cbr = cbr;
+  return OK;
+}
+
 /****************************************************************************
  * Name: up_addrenv_share
  *
@@ -312,72 +495,6 @@ int up_addrenv_share(FAR const _TCB *ptcb, FAR _TCB *ctcb)
   return OK;
 }
 
-/****************************************************************************
- * Name: up_addrenv_instantiate
- *
- * Description:
- *   After an address environment has been established for a task (via
- *   up_addrenv_create().  This function may be called to 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.
- *
- * Input Parameters:
- *   tcb - The TCB of the task or thread whose the address environment will
- *     be instantiated.
- *
- * Returned Value:
- *   A handle that may be used with up_addrenv_restore() to restore the
- *   address environment before up_addrenv_instantiate() was called.
- *
- ****************************************************************************/
-
-FAR void *up_addrenv_instantiate(FAR _TCB *tcb)
-{
-  uint8_t oldcbr;
-  irqstate_t flags;
-
-  /* Get the current CBR value from the CBR register */
-
-  flags = irqsave();
-  oldcbr = inp(Z180_MMU_CBR);
-
-  /* Check if the task has an address environment. */
-
-  if (tcb->xcp.cbr)
-    {
-      /* Yes.. Write the new CBR value into CBR register */
-
-      outp(Z180_MMU_CBR, tcb->xcp.cbr->cbr);
-    }
-
-  irqrestore(flags);
-  return (FAR void *)oldcbr;
-}
-
-/****************************************************************************
- * Name: up_addrenv_restore
- *
- * Description:
- *   Restore an address environment using a handle previously returned by
- *   up_addrenv_instantiate().
- *
- * Input Parameters:
- *   handle - A handle previously returned by up_addrenv_instantiate.
- *
- * Returned Value:
- *   Zero (OK) on success; a negated errno value on failure.
- *
- ****************************************************************************/
-
-int up_addrenv_restore(FAR void *handle)
-{
-  /* Restore the CBR value */
-
-  outp(Z180_MMU_CBR, (uint8_t)handle);
-  return OK;
-}
-
 /****************************************************************************
  * Name: up_addrenv_release
  *
@@ -407,7 +524,7 @@ int up_addrenv_release(FAR _TCB *tcb)
   cbr   = tcb->xcp.cbr;
   if (cbr)
     {
-      /* Nullify the reference to the CBR structgure and decrement the number
+      /* Nullify the reference to the CBR structure and decrement the number
        * of references on the CBR.
        */
 
@@ -419,7 +536,7 @@ int up_addrenv_release(FAR _TCB *tcb)
 
       if (cbr->crefs <= 1)
         {
-          z180_mmu_freecbr(cbr);
+          up_addrenv_destroy(cbr);
         }
       else
         {
diff --git a/include/nuttx/arch.h b/include/nuttx/arch.h
index 7c444602eb4..8b4b10ade9e 100644
--- a/include/nuttx/arch.h
+++ b/include/nuttx/arch.h
@@ -46,6 +46,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <sched.h>
+
 #include <arch/arch.h>
 
 /****************************************************************************
@@ -380,18 +381,48 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size);
 #  define up_getpicbase(ppicbase)
 #endif
 
+/****************************************************************************
+ * Address Environment Interfaces
+ *
+ * Low-level interfaces used in binfmt/ to instantiate tasks with address
+ * environments.  These interfaces all operate on type task_addrenv_t which
+ * is an abstract representation of a task's address environment and must be
+ * defined in arch/arch.h if CONFIG_ADDRENV is defined.
+ *
+ *   up_addrenv_create  - Create an address environment
+ *   up_addrenv_vaddr   - Returns the virtual base address of the address
+ *                        environment
+ *   up_addrenv_select  - Instantiate an address environment
+ *   up_addrenv_restore - Restore an address environment
+ *   up_addrenv_destroy - Destroy an address environment.
+ *   up_addrenv_assign  - Assign an address environment to a TCB
+ *
+ * Higher-level interfaces used by the tasking logic.  These interfaces are
+ * used by the functions in sched/ and all operate on the TCB which as been
+ * assigned an address environment by up_addrenv_assign().
+ *
+ *   up_addrenv_share   - Clone the address environment assigned to one TCB
+ *                        to another.  This operation is done when a pthread
+ *                        is created that share's the same address
+ *                        environment.
+ *   up_addrenv_release - Release the TCBs reference to an address
+ *                        environment when a task/thread exits.
+ *
+ ****************************************************************************/
 /****************************************************************************
  * Name: up_addrenv_create
  *
  * Description:
  *   This function is called from the binary loader logic when a new
- *   task is created in RAM in order to instantiate an address environment for
- *   the task.
+ *   task is created in order to instantiate an address environment for the
+ *   task.  up_addrenv_create is essentially the allocator of the physical
+ *   memory for the new task.
  *
  * Input Parameters:
- *   tcb - The TCB of the task needing the address environment.
  *   envsize - The size (in bytes) of the address environment needed by the
  *     task.
+ *   addrenv - The location to return the representation of the task address
+ *     environment.
  *
  * Returned Value:
  *   Zero (OK) on success; a negated errno value on failure.
@@ -399,7 +430,119 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size);
  ****************************************************************************/
 
 #ifdef CONFIG_ADDRENV
-int up_addrenv_create(FAR _TCB *tcb, size_t envsize);
+int up_addrenv_create(size_t envsize, FAR task_addrenv_t *addrenv);
+#endif
+
+/****************************************************************************
+ * Name: up_addrenv_vaddr
+ *
+ * Description:
+ *   Return the virtual 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.
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *      returned by up_addrenv_create.
+ *   vaddr - The location to return the virtual address.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADDRENV
+int up_addrenv_vaddr(FAR task_addrenv_t addrenv, FAR void **vaddr);
+#endif
+
+/****************************************************************************
+ * Name: up_addrenv_select
+ *
+ * Description:
+ *   After an address environment has been established for a task (via
+ *   up_addrenv_create().  This function may be called to 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.
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *   oldenv
+ *     The address environment that was in place before up_addrenv_select().
+ *     This may be used with up_addrenv_restore() to restore the original
+ *     address environment that was in place before up_addrenv_select() was
+ *     called.  Note that this may be a task agnostic, hardware
+ *     representation that is different from task_addrenv_t.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADDRENV
+int up_addrenv_select(task_addrenv_t addrenv, hw_addrenv_t *oldenv);
+#endif
+
+/****************************************************************************
+ * Name: up_addrenv_restore
+ *
+ * Description:
+ *   After an address environment has been temporarilty instantiated by
+ *   up_addrenv_select, this function may be called to to restore the
+ *   original address environment.
+ *
+ * Input Parameters:
+ *   oldenv - The hardware representation of the address environment
+ *     previously returned by up_addrenv_select.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADDRENV
+int up_addrenv_restore(hw_addrenv_t oldenv);
+#endif
+
+/****************************************************************************
+ * Name: up_addrenv_destroy
+ *
+ * Description:
+ *   Called from the binary loader loader during error handling to destroy
+ *   the address environment previously created by up_addrenv_create().
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADDRENV
+int up_addrenv_destroy(task_addrenv_t addrenv);
+#endif
+
+/****************************************************************************
+ * Name: up_addrenv_assign
+ *
+ * Description:
+ *   Assign an address environment to a TCB.
+ *
+ * Input Parameters:
+ *   addrenv - The representation of the task address environment previously
+ *     returned by up_addrenv_create.
+ *   tcb - The TCB of the task to receive the address environment.
+ *
+ * Returned Value:
+ *   Zero (OK) on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADDRENV
+int up_addrenv_assign(task_addrenv_t addrenv, FAR _TCB *tcb);
 #endif
 
 /****************************************************************************
@@ -424,49 +567,6 @@ int up_addrenv_create(FAR _TCB *tcb, size_t envsize);
 int up_addrenv_share(FAR const _TCB *ptcb, FAR _TCB *ctcb);
 #endif
 
-/****************************************************************************
- * Name: up_addrenv_instantiate
- *
- * Description:
- *   After an address environment has been established for a task (via
- *   up_addrenv_create().  This function may be called to 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.
- *
- * Input Parameters:
- *   tcb - The TCB of the task or thread whose the address environment will
- *     be instantiated.
- *
- * Returned Value:
- *   A handle that may be used with up_addrenv_restore() to restore the
- *   address environment before up_addrenv_instantiate() was called.
- *
- ****************************************************************************/
-
-#ifdef CONFIG_ADDRENV
-FAR void *up_addrenv_instantiate(FAR _TCB *tcb);
-#endif
-
-/****************************************************************************
- * Name: up_addrenv_restore
- *
- * Description:
- *   Restore an address environment using a handle previously returned by
- *   up_addrenv_instantiate().
- *
- * Input Parameters:
- *   handle - A handle previously returned by up_addrenv_instantiate.
- *
- * Returned Value:
- *   Zero (OK) on success; a negated errno value on failure.
- *
- ****************************************************************************/
-
-#ifdef CONFIG_ADDRENV
-int up_addrenv_restore(FAR void *handle);
-#endif
-
 /****************************************************************************
  * Name: up_addrenv_release
  *
diff --git a/include/nuttx/binfmt/binfmt.h b/include/nuttx/binfmt/binfmt.h
index 200823bb843..2e2c6dda8a9 100644
--- a/include/nuttx/binfmt/binfmt.h
+++ b/include/nuttx/binfmt/binfmt.h
@@ -69,7 +69,7 @@ typedef FAR void (*binfmt_dtor_t)(void);
 
 /* This describes the file to be loaded.
  *
- * NOTE: The 'filename' must be the full, absolute path to the file to be
+ * NOTE 1: The 'filename' must be the full, absolute path to the file to be
  * executed unless CONFIG_BINFMT_EXEPATH is defined.  In that case,
  * 'filename' may be a relative path; a set of candidate absolute paths
  * will be generated using the PATH environment variable and load_module()
@@ -81,7 +81,7 @@ struct binary_s
 {
   /* Information provided to the loader to load and bind a module */
 
-  FAR const char *filename;            /* Full path to the binary to be loaded (See NOTE above) */
+  FAR const char *filename;            /* Full path to the binary to be loaded (See NOTE 1 above) */
   FAR const char **argv;               /* Argument list */
   FAR const struct symtab_s *exports;  /* Table of exported symbols */
   int nexports;                        /* The number of symbols in exports[] */