Implement SD-based paging for EA3131

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2931 42af7a65-404d-4744-a932-0658087f49c3

ChangeLog

@@ -1266,3 +1266,11 @@
 	  data and prefectch aborts which are within this zeroed region.
 
 5.11 2010-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
+
+	* configs/ea3131/src/up_fillpage.c - Added new configuration item
+	  CONFIG_PAGING_BINPATH.  If CONFIG_PAGING_BINPATH is defined, then it
+	  is the full path to a file on a mounted file system that contains
+	  a binary image of the NuttX executable.  Pages will be filled by
+	  reading from offsets into this file that correspond to virtual
+	  fault addresses.  up_fillpage.c implements logic to perform page
+	  files using the CONFIG_PAGING_BINPATH file.

Documentation/NuttX.html

@@ -8,7 +8,7 @@
   <tr align="center" bgcolor="#e4e4e4">
     <td>
       <h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
-      <p>Last Updated: September 7, 2010</p>
+      <p>Last Updated: September 8, 2010</p>
     </td>
   </tr>
 </table>
@@ -1950,6 +1950,14 @@ buildroot-1.8 2009-12-21 &lt;spudmonkey@racsa.co.cr&gt;
 <ul><pre>
 nuttx-5.11 2010-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
+	* configs/ea3131/src/up_fillpage.c - Added new configuration item
+	  CONFIG_PAGING_BINPATH.  If CONFIG_PAGING_BINPATH is defined, then it
+	  is the full path to a file on a mounted file system that contains
+	  a binary image of the NuttX executable.  Pages will be filled by
+	  reading from offsets into this file that correspond to virtual
+	  fault addresses.  up_fillpage.c implements logic to perform page
+	  files using the CONFIG_PAGING_BINPATH file.
+
 pascal-2.1 2010-xx-xx Gregory Nutt &lt;spudmonkey@racsa.co.cr&gt;
 
 buildroot-1.9 2010-xx-xx <spudmonkey@racsa.co.cr>

Documentation/NuttxPortingGuide.html

@@ -12,7 +12,7 @@
       <h1><big><font color="#3c34ec">
         <i>NuttX RTOS Porting Guide</i>
       </font></big></h1>
-      <p>Last Updated: August 29, 2010</p>
+      <p>Last Updated: September 8, 2010</p>
     </td>
   </tr>
 </table>
@@ -2294,6 +2294,7 @@ build
 </ul>
 
 <h2>General OS setup</h2>
+<ul>
   <li>
     <code>CONFIG_DEBUG</code>: enables built-in debug options
   </li>
@@ -2569,6 +2570,11 @@ build
     <code>CONFIG_PAGING_VECL2VADDR</code>:
     This is the virtual address of the L2 page table entry to use for the vector mapping.
   </li>
+  <li>
+    <code>CONFIG_PAGING_BINPATH</code>:
+    If <code>CONFIG_PAGING_BINPATH</code> is defined, then it is the full path to a file on a mounted file system that contains a binary image of the NuttX executable.
+    Pages will be filled by reading from offsets into this file that correspond to virtual fault addresses.
+  </li>
 </ul>
 <p>
   The following can be used to disable categories of APIs supported

configs/README.txt

@@ -401,6 +401,11 @@ defconfig -- This is a configuration file similar to the Linux
 		  page table entry to use for the vector mapping.
 		CONFIG_PAGING_VECL2VADDR - This is the virtual address of the L2
 		  page table entry to use for the vector mapping.
+		CONFIG_PAGING_BINPATH - If CONFIG_PAGING_BINPATH is defined, then it
+		  is the full path to a file on a mounted file system that contains
+		  a binary image of the NuttX executable.  Pages will be filled by
+		  reading from offsets into this file that correspond to virtual
+		  fault addresses.
 
 	The following can be used to disable categories of APIs supported
 	by the OS.  If the compiler supports weak functions, then it

configs/ea3131/README.txt

@@ -416,8 +416,41 @@ On-Demand Paging
      The references and issues related to this are discussed in (2)
      and (3) above.
 
+  Alternative:
+  ------------
+
+  I have implemented an alternative within configs/ea3131/src/up_fillpage.c
+  which is probably only useful for testing.  Here is the usage module
+  for this alternative
+
+  1. Place the nuttx.bin file on an SD card.
+  2. Insert the SD card prior to booting
+  3. In up_fillpage(), use the virtual miss address (minus the virtual
+     base address) as an offset into the nuttx.bin file, and read the
+     required page from that offset in the nuttx.bin file:
+
+     off_t offset = (off_t)vpage - PG_LOCKED_VBASE;
+     off_t pos    = lseek(fd, offset, SEEK_SET);
+     if (pos != (off_t)-1)
+       {
+         int ret = read(fd, vpage, PAGESIZE);
+       }
+
+  In this way, the paging implementation can do on-demand paging
+  from an image file on the SD card.  Problems/issues with this
+  approach probably make it only useful for testing:
+
+  1. You would still have to boot the locked section over serial or
+     using a bootloader -- it is not clear how the power up boot
+     would occur.  For testing, the nuttx.bin file could be both
+     provided on the SD card and loaded over serial. 
+  2. If the SD card is not in place, the system will crash.
+  3. This means that all of the file system logic and FAT file
+     system would have to reside in the locked text region.
+
 ARM/EA3131-specific Configuration Options
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 	CONFIG_ARCH - Identifies the arch/ subdirectory.  This should
 	   be set to:
 
@@ -500,7 +533,7 @@ ARM/EA3131-specific Configuration Options
 
 	CONFIG_LPC313X_MCI, CONFIG_LPC313X_SPI, CONFIG_LPC313X_UART
 
-  xernal memory available on the board (see also CONFIG_MM_REGIONS)
+  External memory available on the board (see also CONFIG_MM_REGIONS)
 
 	CONFIG_LPC313X_EXTSRAM0 - Select if external SRAM0 is present
 	CONFIG_LPC313X_EXTSRAM0HEAP - Select if external SRAM0 should be

configs/ea3131/locked/mklocked.sh

@@ -86,6 +86,7 @@ function checkzero () {
 		echo "n"
 	fi
 }
+
 ############################################################################
 # Interrupt Handlers
 ############################################################################

configs/ea3131/src/up_fillpage.c

@@ -47,15 +47,38 @@
 #include <nuttx/page.h>
 
 #ifdef CONFIG_PAGING
+#ifdef CONFIG_PAGING_BINPATH
+#  include <sys/stat.h>
+#  include <sys/types.h>
+#  include <stdbool.h>
+#  include <unistd.h>
+#  include <fcntl.h>
+#endif
 
 /****************************************************************************
  * Definitions
  ****************************************************************************/
 
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+#ifdef CONFIG_PAGING_BINPATH
+struct pg_source_s
+{
+  bool initialized;  /* TRUE: we are initialized */
+  int  fd;           /* File descriptor of the nuttx.bin file */
+};
+#endif
+
 /****************************************************************************
  * Private Data
  ****************************************************************************/
 
+#ifdef CONFIG_PAGING_BINPATH
+static struct pg_source_s g_pgsrc;
+#endif
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -117,20 +140,80 @@
  ****************************************************************************/
 
 #ifdef CONFIG_PAGING_BLOCKINGFILL
+
+/* Version 1:  Supports blocking fill operations */
+
 int up_fillpage(FAR _TCB *tcb, FAR void *vpage)
 {
+#ifdef CONFIG_PAGING_BINPATH
+  ssize_t nbytes;
+  off_t   offset;
+  off_t   pos;
+#endif
+
   pglldbg("TCB: %p vpage: %p far: %08x\n", tcb, vpage, tcb->xcp.far);
+  DEBUGASSERT(tcb->xcp.far >= PG_PAGED_VBASE && tcb->xcp.far < PG_PAGED_VEND);
+
+  /* If BINPATH is defined, then it is the full path to a file on a mounted file
+   * system.  In this caseinitialization will be deferred until the first
+   * time that up_fillpage() is called.  Are we initialized?
+   */
+
+#ifdef CONFIG_PAGING_BINPATH
+
+  if (!g_pgsrc.initialized)
+    {
+      /* Open the selected path for read-only access */
+
+      g_pgsrc.fd = open(CONFIG_PAGING_BINPATH, O_RDONLY);
+      DEBUGASSERT(g_pgsrc.fd >= 0);
+      g_pgsrc.initialized = true;
+    }
+
+  /* Create an offset into the binary image that corresponds to the 
+   * virtual address.   File offset 0 corresponds to PG_LOCKED_VBASE.
+   */
+
+  offset = (off_t)vpage - PG_LOCKED_VBASE;
+
+  /* Seek to that position */
+
+  pos = lseek(g_pgsrc.fd, offset, SEEK_SET);
+  DEBUGASSERT(pos != (off_t)-1);
+  
+  /* And read the page data from that offset */
+
+  nbytes = read(g_pgsrc.fd, vpage, PAGESIZE);
+  DEBUGASSERT(nbytes == PAGESIZE);
+  return OK;
+
+#else /* CONFIG_PAGING_BINPATH */
+
 # warning "Not implemented"
   return -ENOSYS;
+
+#endif /* CONFIG_PAGING_BINPATH */
 }
+
 #else
+
+/* Version 2:  Supports non-blocking, asynchronous fill operations */
+
 int up_fillpage(FAR _TCB *tcb, FAR void *vpage, up_pgcallback_t pg_callback)
 {
   pglldbg("TCB: %p vpage: %d far: %08x\n", tcb, vpage, tcb->xcp.far);
-# warning "Not implemented"
+  DEBUGASSERT(tcb->xcp.far >= PG_PAGED_VBASE && tcb->xcp.far < PG_PAGED_VEND);
+
+#ifdef CONFIG_PAGING_BINPATH
+#  error "File system-based paging must always be implemented with blocking calls"
+#else
+#  warning "Not implemented"
+#endif
+
   return -ENOSYS;
 }
-#endif
+
+#endif /* CONFIG_PAGING_BLOCKINGFILL */
 
 /************************************************************************************
  * Name: lpc313x_pginitialize
@@ -154,6 +237,16 @@ void weak_function lpc313x_pginitialize(void)
    * - Do whatever else is necessary to make up_fillpage() ready for the first time
    *   that it is called.
    */
+
+#ifdef CONFIG_PAGING_BINPATH
+  /* If BINPATH is defined, then it is the full path to a file on a mounted file
+   * system.  However, in this case, initialization will involve some higher level
+   * file system operations.  Since this function is called from a low level (before
+   * os_start() is even called), it may not be possible to perform file system
+   * operations yet.  Therefore, initialization will be deferred until the first
+   * time that up_fillpage() is called.
+   */
+#endif
 }
 
 #endif /* CONFIG_PAGING */