Fix an uninitialized register error that crept into the ARM9 start up code many years ago and was recently cloned into the Cortex-A5. Obviously no on has used NuttX with ARM9 for years

ChangeLog

@@ -5196,3 +5196,8 @@
 	  configuration logic for USARTs needs to depend on if the USART is
 	  configured as a UART or not.  And this is for all CPUS, not just
 	  SAM3/4 (2013-7-24).
+	* arch/arm/src/arm/up_head.S and arch/arm/src/armv7-a/arm_head.S:
+	  Fix a bug (uninitialized register error) that crept in the ARM9
+	  boot-up code several years ago and was cloned into the Cortex-A5
+	  code.  Obviously no one has used the ARM9 NuttX port for years!
+

arch/arm/src/arm/up_head.S

@@ -309,8 +309,14 @@ __start:
 
 #else /* CONFIG_PAGING */
 
+#ifdef CONFIG_IDENTITY_TEXTMAP
+	mksection r0, r4				/* r0=phys. base section */
+	ldr		r1, .LCmmuflags			/* FLGS=MMU_MEMFLAGS */
+	add		r3, r1, r0				/* r3=flags + base */
+#endif
+
 	/* Create a virtual single section mapping for the first MB of the .text
-	 * address space. Now, we have the first 1MB mapping to both phyical and
+	 * address space. Now, we have the first 1MB mapping to both physical and
 	 * virtual addresses.  The rest of the .text mapping will be completed in
 	 * .Lvstart once we have moved the physical mapping out of the way.
 	 *
@@ -500,7 +506,6 @@ __start:
 	 * cover additinal RAM sections.
 	 */
 
-
 #ifndef CONFIG_ARCH_ROMPGTABLE
 #ifndef CONFIG_IDENTITY_TEXTMAP
 	ldr		r4, .LCvpgtable			/* r4=virtual page table */
@@ -658,4 +663,3 @@ g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
 	.size	g_idle_topstack, .-g_idle_topstack
 	.end
-

arch/arm/src/armv7-a/arm_head.S

@@ -315,8 +315,18 @@ __start:
 
 #else /* CONFIG_PAGING */
 
+	/* Create identity mapping for first MB of the .text section if we have
+	 * no already done so.
+	 */
+
+#ifdef CONFIG_IDENTITY_TEXTMAP
+	mksection r0, r4				/* r0=phys. base section */
+	ldr		r1, .LCmmuflags			/* FLGS=MMU_MEMFLAGS */
+	add		r3, r1, r0				/* r3=flags + base */
+#endif
+
 	/* Create a virtual single section mapping for the first MB of the .text
-	 * address space. Now, we have the first 1MB mapping to both phyical and
+	 * address space. Now, we have the first 1MB mapping to both physical and
 	 * virtual addresses.  The rest of the .text mapping will be completed in
 	 * .Lvstart once we have moved the physical mapping out of the way.
 	 *
@@ -573,7 +583,6 @@ __start:
 	 * cover additinal RAM sections.
 	 */
 
-
 #ifndef CONFIG_ARCH_ROMPGTABLE
 #ifndef CONFIG_IDENTITY_TEXTMAP
 	ldr		r4, .LCvpgtable			/* r4=virtual page table */

configs/sama5d3x-ek/README.txt

@@ -67,7 +67,7 @@ Contents
   - Configurations
 
 Contents
-^^^^^^^^
+========
 
   - PIO Muliplexing
   - Development Environment
@@ -76,6 +76,7 @@ Contents
   - NuttX EABI "buildroot" Toolchain
   - NuttX OABI "buildroot" Toolchain
   - NXFLAT Toolchain
+  - Loading Code
   - Buttons and LEDs
   - Serial Consoles
   - SAMA5D3x-EK Configuration Options
@@ -102,7 +103,7 @@ Development Environment
   toolchains will likely cause problems.
 
 GNU Toolchain Options
-^^^^^^^^^^^^^^^^^^^^^
+=====================
 
   The NuttX make system will support the several different toolchain options.
 
@@ -164,7 +165,7 @@ GNU Toolchain Options
   path or will get the wrong version of make.
 
 IDEs
-^^^^
+====
 
   NuttX is built using command-line make.  It can be used with an IDE, but some
   effort will be required to create the project (There is a simple RIDE project
@@ -197,7 +198,7 @@ IDEs
   startup object needed by RIDE.
 
 NuttX EABI "buildroot" Toolchain
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+================================
 
   A GNU GCC-based toolchain is assumed.  The files */setenv.sh should
   be modified to point to the correct path to the Cortex-M3 GCC toolchain (if
@@ -240,7 +241,7 @@ NuttX EABI "buildroot" Toolchain
   See instructions below.
 
 NuttX OABI "buildroot" Toolchain
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+================================
 
   The older, OABI buildroot toolchain is also available.  To use the OABI
   toolchain, use the build instructtions above, but (1) modify the
@@ -249,7 +250,7 @@ NuttX OABI "buildroot" Toolchain
   cortexm3-defconfig-4.3.3
 
 NXFLAT Toolchain
-^^^^^^^^^^^^^^^^
+================
 
   If you are *not* using the NuttX buildroot toolchain and you want to use
   the NXFLAT tools, then you will still have to build a portion of the buildroot
@@ -281,8 +282,33 @@ NXFLAT Toolchain
   8. Edit setenv.h, if necessary, so that the PATH variable includes
      the path to the newly built NXFLAT binaries.
 
+Loading Code
+============
+
+  Loading code with the Segger tools and GDB
+  ------------------------------------------
+
+    1) Change directories into the directory where you built NuttX.
+    2) Start the GDB server and wait until it is ready to accept GDB
+       connections.
+    3) Then run GDB like this:
+
+         $ arm-none-eabi-gdb
+         (gdb) target remote localhost:2331
+         (gdb) mon reset
+         (gdb) load nuttx
+         (gdb) ... start debugging ...
+
+  Loading code using J-Link Commander
+  ----------------------------------
+
+    J-Link> r
+    J-Link> loadbin <file> <address>
+    J-Link> setpc <address of __start>
+    J-Link> ... start debugging ...
+
 Buttons and LEDs
-^^^^^^^^^^^^^^^^
+================
 
   Buttons
   -------