Rename g_heapbase to g_idle_topstack; Fix kernel build heap allocation which cannot use g_heapbase

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5739 42af7a65-404d-4744-a932-0658087f49c3

24 files changed, 115 insertions, 99 deletions

diff --git a/nuttx/arch/arm/src/arm/up_assert.c b/nuttx/arch/arm/src/arm/up_assert.c
index d97aba5ea..e5bf00d6e 100644
--- a/nuttx/arch/arm/src/arm/up_assert.c
+++ b/nuttx/arch/arm/src/arm/up_assert.c
@@ -174,7 +174,7 @@ static void up_dumpstate(void)
 
   if (rtcb->pid == 0)
     {
-      ustackbase = g_heapbase - 4;
+      ustackbase = g_idle_topstack - 4;
       ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
     }
   else
diff --git a/nuttx/arch/arm/src/arm/up_head.S b/nuttx/arch/arm/src/arm/up_head.S
index 46efd8772..ef911d0b6 100644
--- a/nuttx/arch/arm/src/arm/up_head.S
+++ b/nuttx/arch/arm/src/arm/up_head.S
@@ -610,7 +610,7 @@ __start:
 	 *
 	 * The idle task stack starts at the end of BSS and is of size
 	 * CONFIG_IDLETHREAD_STACKSIZE.  The heap continues from there until the
-	 * end of memory.  See g_heapbase below.
+	 * end of memory.  See g_idle_topstack below.
 	 */
 
 .Linitparms:
@@ -645,17 +645,17 @@ __start:
 
 	 /* Data section variables */
 
-	/* This global variable is unsigned long g_heapbase and is
+	/* This global variable is unsigned long g_idle_topstack and is
 	 * exported from here only because of its coupling to .Linitparms
 	 * above.
 	 */
 
 	.data
 	.align	4
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 	.end
 
diff --git a/nuttx/arch/arm/src/arm/up_nommuhead.S b/nuttx/arch/arm/src/arm/up_nommuhead.S
index aac95b73a..e3f5a94e6 100644
--- a/nuttx/arch/arm/src/arm/up_nommuhead.S
+++ b/nuttx/arch/arm/src/arm/up_nommuhead.S
@@ -135,7 +135,7 @@ __start:
 	 * _ebss is the end of the BSS regsion (see ld.script)
 	 * The idle task stack starts at the end of BSS and is
 	 * of size CONFIG_IDLETHREAD_STACKSIZE.  The heap continues
-	 * from there until the end of memory.  See g_heapbase
+	 * from there until the end of memory.  See g_idle_topstack
 	 * below.
 	 */
 
@@ -150,18 +150,18 @@ LC2:	.long	_eronly	/* Where .data defaults are stored in FLASH */
 #endif
 	.size	__start, .-__start
 
-	/* This global variable is unsigned long g_heapbase and is
+	/* This global variable is unsigned long g_idle_topstack and is
 	 * exported from here only because of its coupling to LCO
 	 * above.
 	 */
 
 	.data
 	.align	4
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
 
diff --git a/nuttx/arch/arm/src/armv6-m/up_assert.c b/nuttx/arch/arm/src/armv6-m/up_assert.c
index 15ba1f53f..de5e5f6a1 100644
--- a/nuttx/arch/arm/src/armv6-m/up_assert.c
+++ b/nuttx/arch/arm/src/armv6-m/up_assert.c
@@ -181,7 +181,7 @@ static void up_dumpstate(void)
 
   if (rtcb->pid == 0)
     {
-      ustackbase = g_heapbase - 4;
+      ustackbase = g_idle_topstack - 4;
       ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
     }
   else
diff --git a/nuttx/arch/arm/src/armv7-m/mpu.h b/nuttx/arch/arm/src/armv7-m/mpu.h
index 74bfe7a9e..7e2e6bb77 100644
--- a/nuttx/arch/arm/src/armv7-m/mpu.h
+++ b/nuttx/arch/arm/src/armv7-m/mpu.h
@@ -66,7 +66,7 @@
 /* MPU Type Register Bit Definitions */
 
 #define MPU_TYPE_SEPARATE       (1 << 0) /* Bit 0: 0:unified or 1:separate memory maps */
-#define MPU_TYPE_DREGION_SHIFT  (8)      /* Bits 8-15: Number MPU data regsion */
+#define MPU_TYPE_DREGION_SHIFT  (8)      /* Bits 8-15: Number MPU data regions */
 #define MPU_TYPE_DREGION_MASK   (0xff << MPU_TYPE_DREGION_SHIFT)
 #define MPU_TYPE_IREGION_SHIFT  (16)     /* Bits 16-23: Number MPU instruction regions */
 #define MPU_TYPE_IREGION_MASK   (0xff << MPU_TYPE_IREGION_SHIFT)
@@ -104,11 +104,11 @@
 #  define MPU_RASR_SRD_5        (0x20 << MPU_RASR_SRD_SHIFT)
 #  define MPU_RASR_SRD_6        (0x40 << MPU_RASR_SRD_SHIFT)
 #  define MPU_RASR_SRD_7        (0x80 << MPU_RASR_SRD_SHIFT)
-#define MPU_RASR_ATTR_SHIFT     (21)      /* Bits 19-21: TEX Address Permisson */
-#define MPU_RASR_ATTR__MASK     (7 << MPU_RASR_ATTR_SHIFT)
-#define MPU_RASR_S              (1 << 18) /* Bit 18: Shareable */
-#define MPU_RASR_C              (1 << 17) /* Bit 17: Cacheable */
 #define MPU_RASR_B              (1 << 16) /* Bit 16: Bufferable */
+#define MPU_RASR_C              (1 << 17) /* Bit 17: Cacheable */
+#define MPU_RASR_S              (1 << 18) /* Bit 18: Shareable */
+#define MPU_RASR_ATTR_SHIFT     (19)      /* Bits 19-21: TEX Address Permisson */
+#define MPU_RASR_ATTR_MASK      (7 << MPU_RASR_ATTR_SHIFT)
 #define MPU_RASR_AP_SHIFT       (24)      /* Bits 24-26: Access permission */
 #define MPU_RASR_AP_MASK        (7 << MPU_RASR_AP_SHIFT)
 #  define MPU_RASR_AP_NONO      (0 << MPU_RASR_AP_SHIFT) /* P:None U:None */
diff --git a/nuttx/arch/arm/src/armv7-m/up_assert.c b/nuttx/arch/arm/src/armv7-m/up_assert.c
index 394c6858f..a4a58639c 100644
--- a/nuttx/arch/arm/src/armv7-m/up_assert.c
+++ b/nuttx/arch/arm/src/armv7-m/up_assert.c
@@ -180,7 +180,7 @@ static void up_dumpstate(void)
 
   if (rtcb->pid == 0)
     {
-      ustackbase = g_heapbase - 4;
+      ustackbase = g_idle_topstack - 4;
       ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
     }
   else
diff --git a/nuttx/arch/arm/src/common/up_allocateheap.c b/nuttx/arch/arm/src/common/up_allocateheap.c
index 12cbfcfa8..617bffd2e 100644
--- a/nuttx/arch/arm/src/common/up_allocateheap.c
+++ b/nuttx/arch/arm/src/common/up_allocateheap.c
@@ -82,6 +82,6 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size = CONFIG_DRAM_END - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size = CONFIG_DRAM_END - g_idle_topstack;
 }
diff --git a/nuttx/arch/arm/src/common/up_internal.h b/nuttx/arch/arm/src/common/up_internal.h
index 6e874b2ca..1a7c1e304 100644
--- a/nuttx/arch/arm/src/common/up_internal.h
+++ b/nuttx/arch/arm/src/common/up_internal.h
@@ -166,7 +166,7 @@ extern volatile uint32_t *current_regs;
  * CONFIG_DRAM_END
  */
 
-extern const uint32_t g_heapbase;
+extern const uint32_t g_idle_topstack;
 
 /* Address of the saved user stack pointer */
 
diff --git a/nuttx/arch/arm/src/dm320/dm320_allocateheap.c b/nuttx/arch/arm/src/dm320/dm320_allocateheap.c
index 1383b93da..27a7e7a90 100644
--- a/nuttx/arch/arm/src/dm320/dm320_allocateheap.c
+++ b/nuttx/arch/arm/src/dm320/dm320_allocateheap.c
@@ -85,6 +85,6 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = (DM320_SDRAM_VADDR + CONFIG_DRAM_SIZE) - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = (DM320_SDRAM_VADDR + CONFIG_DRAM_SIZE) - g_idle_topstack;
 }
diff --git a/nuttx/arch/arm/src/imx/imx_allocateheap.c b/nuttx/arch/arm/src/imx/imx_allocateheap.c
index 37b05eb7f..f94a7fe44 100644
--- a/nuttx/arch/arm/src/imx/imx_allocateheap.c
+++ b/nuttx/arch/arm/src/imx/imx_allocateheap.c
@@ -86,8 +86,8 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = (IMX_SDRAM_VSECTION + CONFIG_DRAM_SIZE) - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = (IMX_SDRAM_VSECTION + CONFIG_DRAM_SIZE) - g_idle_topstack;
 }
 
 /****************************************************************************
diff --git a/nuttx/arch/arm/src/kinetis/kinetis_vectors.S b/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
index 7fa223615..11ac46221 100644
--- a/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
+++ b/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
@@ -738,13 +738,13 @@ g_intstackbase:
  * and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread is the thread that
  * the system boots on and, eventually, becomes the idle, do nothing task that runs
  * only when there is nothing else to run.  The heap continues from there until the
- * end of memory.  See g_heapbase below.
+ * end of memory.  See g_idle_topstack below.
  */
 
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.word	HEAP_BASE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
diff --git a/nuttx/arch/arm/src/lm/lm_vectors.S b/nuttx/arch/arm/src/lm/lm_vectors.S
index 1d3553b4e..0f4300065 100644
--- a/nuttx/arch/arm/src/lm/lm_vectors.S
+++ b/nuttx/arch/arm/src/lm/lm_vectors.S
@@ -336,13 +336,13 @@ g_intstackbase:
  * and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread is the thread that
  * the system boots on and, eventually, becomes the idle, do nothing task that runs
  * only when there is nothing else to run.  The heap continues from there until the
- * end of memory.  See g_heapbase below.
+ * end of memory.  See g_idle_topstack below.
  */
 
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_allocateheap.c b/nuttx/arch/arm/src/lpc17xx/lpc17_allocateheap.c
index f316570f5..047edf5e3 100644
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_allocateheap.c
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_allocateheap.c
@@ -198,9 +198,12 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
 #if defined(CONFIG_NUTTX_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
-  /* Get the unaligned size of the user-space heap */
+  /* Get the unaligned size and position of the user-space heap.
+   * This heap begins after the user-space .bss section at an offset
+   * of CONFIG_MM_KERNEL_HEAPSIZE (subject to alignment).
+   */
 
-  uintptr_t ubase = (uintptr_t)g_heapbase + CONFIG_MM_KERNEL_HEAPSIZE;
+  uintptr_t ubase = (uintptr_t)USERSPACE->us_bssend + CONFIG_MM_KERNEL_HEAPSIZE;
   size_t    usize = CONFIG_DRAM_END - ubase;
   int       log2;
 
@@ -231,8 +234,8 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
   /* Return the heap settings */
 
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = CONFIG_DRAM_END - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = CONFIG_DRAM_END - g_idle_topstack;
 #endif
 }
 
@@ -249,9 +252,12 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 #if defined(CONFIG_NUTTX_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
 void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
 {
-  /* Get the unaligned size of the user-space heap */
+  /* Get the unaligned size and position of the user-space heap.
+   * This heap begins after the user-space .bss section at an offset
+   * of CONFIG_MM_KERNEL_HEAPSIZE (subject to alignment).
+   */
 
-  uintptr_t ubase = (uintptr_t)g_heapbase + CONFIG_MM_KERNEL_HEAPSIZE;
+  uintptr_t ubase = (uintptr_t)USERSPACE->us_bssend + CONFIG_MM_KERNEL_HEAPSIZE;
   size_t    usize = CONFIG_DRAM_END - ubase;
   int       log2;
 
@@ -268,10 +274,12 @@ void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
   usize = (1 << log2);
   ubase = CONFIG_DRAM_END - usize;
 
-  /* Return the kernel heap settings */
+  /* Return the kernel heap settings (i.e., the part of the heap region
+   * that was not dedicated to the user heap).
+   */
 
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = ubase - (uintptr_t)g_heapbase;
+  *heap_start = (FAR void*)USERSPACE->us_bssend;
+  *heap_size  = ubase - (uintptr_t)USERSPACE->us_bssend;
 }
 #endif
 
diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S b/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
index 25d2e7f19..eca382b1b 100644
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
@@ -417,13 +417,13 @@ g_intstackbase:
  * and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread is the thread that
  * the system boots on and, eventually, becomes the idle, do nothing task that runs
  * only when there is nothing else to run.  The heap continues from there until the
- * end of memory.  See g_heapbase below.
+ * end of memory.  See g_idle_topstack below.
  */
 
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.word	HEAP_BASE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
diff --git a/nuttx/arch/arm/src/lpc214x/lpc214x_head.S b/nuttx/arch/arm/src/lpc214x/lpc214x_head.S
index 678481154..ea2ea1220 100644
--- a/nuttx/arch/arm/src/lpc214x/lpc214x_head.S
+++ b/nuttx/arch/arm/src/lpc214x/lpc214x_head.S
@@ -604,7 +604,7 @@ __start:
 	 * _ebss is the end of the BSS regsion (see ld.script)
 	 * The idle task stack starts at the end of BSS and is
 	 * of size CONFIG_IDLETHREAD_STACKSIZE.  The heap continues
-	 * from there until the end of memory.  See g_heapbase
+	 * from there until the end of memory.  See g_idle_topstack
 	 * below.
 	 */
 
@@ -617,18 +617,18 @@ LC2:	.long	_eronly	/* Where .data defaults are stored in FLASH */
 	.long	_edata
 	.size	__start, .-__start
 
-	/* This global variable is unsigned long g_heapbase and is
+	/* This global variable is unsigned long g_idle_topstack and is
 	 * exported from here only because of its coupling to LCO
 	 * above.
 	 */
 
 	.data
 	.align	4
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
 
diff --git a/nuttx/arch/arm/src/lpc2378/lpc23xx_head.S b/nuttx/arch/arm/src/lpc2378/lpc23xx_head.S
index a4cab8f05..578b77753 100755
--- a/nuttx/arch/arm/src/lpc2378/lpc23xx_head.S
+++ b/nuttx/arch/arm/src/lpc2378/lpc23xx_head.S
@@ -204,7 +204,7 @@ __start:
 	 * _ebss is the end of the BSS regsion (see ld.script)
 	 * The idle task stack starts at the end of BSS and is
 	 * of size CONFIG_IDLETHREAD_STACKSIZE.  The heap continues
-	 * from there until the end of memory.  See g_heapbase
+	 * from there until the end of memory.  See g_idle_topstack
 	 * below.
 	 */
 
@@ -217,18 +217,18 @@ LC2:	.long	_eronly	/* Where .data defaults are stored in FLASH */
 	.long	_edata
 	.size	__start, .-__start
 
-	/* This global variable is unsigned long g_heapbase and is
+	/* This global variable is unsigned long g_idle_topstack and is
 	 * exported from here only because of its coupling to LCO
 	 * above.
 	 */
 
 	.data
 	.align	4
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 	
 	.end
 
diff --git a/nuttx/arch/arm/src/lpc31xx/lpc31_allocateheap.c b/nuttx/arch/arm/src/lpc31xx/lpc31_allocateheap.c
index f57c343ef..7c2c8696a 100644
--- a/nuttx/arch/arm/src/lpc31xx/lpc31_allocateheap.c
+++ b/nuttx/arch/arm/src/lpc31xx/lpc31_allocateheap.c
@@ -180,8 +180,8 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = LPC31_HEAP_VEND - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = LPC31_HEAP_VEND - g_idle_topstack;
 }
 
 /************************************************************************
diff --git a/nuttx/arch/arm/src/lpc43xx/lpc43_allocateheap.c b/nuttx/arch/arm/src/lpc43xx/lpc43_allocateheap.c
index c33f9f1ed..4d9d7b21c 100644
--- a/nuttx/arch/arm/src/lpc43xx/lpc43_allocateheap.c
+++ b/nuttx/arch/arm/src/lpc43xx/lpc43_allocateheap.c
@@ -211,10 +211,10 @@
  * thread is the thread that the system boots on and, eventually, becomes the
  * idle, do nothing task that runs only when there is nothing else to run.
  * The heap continues from there until the configured end of memory.
- * g_heapbase is the beginning of this heap region (not necessarily aligned).
+ * g_idle_topstack is the beginning of this heap region (not necessarily aligned).
  */
 
-const uint32_t g_heapbase = (uint32_t)&_ebss + CONFIG_IDLETHREAD_STACKSIZE;
+const uint32_t g_idle_topstack = (uint32_t)&_ebss + CONFIG_IDLETHREAD_STACKSIZE;
 
 /****************************************************************************
  * Private Functions
@@ -244,8 +244,8 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
   /* Start with the first SRAM region */
 
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size = CONFIG_DRAM_END - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size = CONFIG_DRAM_END - g_idle_topstack;
 }
 
 /************************************************************************
diff --git a/nuttx/arch/arm/src/nuc1xx/nuc_start.c b/nuttx/arch/arm/src/nuc1xx/nuc_start.c
index 67c06c7a5..fa5f249a3 100644
--- a/nuttx/arch/arm/src/nuc1xx/nuc_start.c
+++ b/nuttx/arch/arm/src/nuc1xx/nuc_start.c
@@ -77,7 +77,7 @@
  * Public Data
  ****************************************************************************/
 
-const uint32_t g_heapbase = HEAP_BASE;
+const uint32_t g_idle_topstack = HEAP_BASE;
 
 /****************************************************************************
  * Private Functions
diff --git a/nuttx/arch/arm/src/sam3u/sam3u_allocateheap.c b/nuttx/arch/arm/src/sam3u/sam3u_allocateheap.c
index 86d5fbf36..576fae802 100644
--- a/nuttx/arch/arm/src/sam3u/sam3u_allocateheap.c
+++ b/nuttx/arch/arm/src/sam3u/sam3u_allocateheap.c
@@ -109,9 +109,12 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
 #if defined(CONFIG_NUTTX_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
-  /* Get the unaligned size of the user-space heap */
+  /* Get the unaligned size and position of the user-space heap.
+   * This heap begins after the user-space .bss section at an offset
+   * of CONFIG_MM_KERNEL_HEAPSIZE (subject to alignment).
+   */
 
-  uintptr_t ubase = (uintptr_t)g_heapbase + CONFIG_MM_KERNEL_HEAPSIZE;
+  uintptr_t ubase = (uintptr_t)USERSPACE->us_bssend + CONFIG_MM_KERNEL_HEAPSIZE;
   size_t    usize = CONFIG_DRAM_END - ubase;
   int       log2;
 
@@ -142,8 +145,8 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
   /* Return the heap settings */
 
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = CONFIG_DRAM_END - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = CONFIG_DRAM_END - g_idle_topstack;
 #endif
 }
 
@@ -160,9 +163,12 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 #if defined(CONFIG_NUTTX_KERNEL) && defined(CONFIG_MM_KERNEL_HEAP)
 void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
 {
-  /* Get the unaligned size of the user-space heap */
+  /* Get the unaligned size and position of the user-space heap.
+   * This heap begins after the user-space .bss section at an offset
+   * of CONFIG_MM_KERNEL_HEAPSIZE (subject to alignment).
+   */
 
-  uintptr_t ubase = (uintptr_t)g_heapbase + CONFIG_MM_KERNEL_HEAPSIZE;
+  uintptr_t ubase = (uintptr_t)USERSPACE->us_bssend + CONFIG_MM_KERNEL_HEAPSIZE;
   size_t    usize = CONFIG_DRAM_END - ubase;
   int       log2;
 
@@ -179,10 +185,12 @@ void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
   usize = (1 << log2);
   ubase = CONFIG_DRAM_END - usize;
 
-  /* Return the kernel heap settings */
+  /* Return the kernel heap settings (i.e., the part of the heap region
+   * that was not dedicated to the user heap).
+   */
 
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = ubase - (uintptr_t)g_heapbase;
+  *heap_start = (FAR void*)USERSPACE->us_bssend;
+  *heap_size  = ubase - (uintptr_t)USERSPACE->us_bssend;
 }
 #endif
 
diff --git a/nuttx/arch/arm/src/sam3u/sam3u_vectors.S b/nuttx/arch/arm/src/sam3u/sam3u_vectors.S
index ec0287e34..eba6edd3a 100644
--- a/nuttx/arch/arm/src/sam3u/sam3u_vectors.S
+++ b/nuttx/arch/arm/src/sam3u/sam3u_vectors.S
@@ -443,13 +443,13 @@ g_intstackbase:
  * and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread is the thread that
  * the system boots on and, eventually, becomes the idle, do nothing task that runs
  * only when there is nothing else to run.  The heap continues from there until the
- * end of memory.  See g_heapbase below.
+ * end of memory.  See g_idle_topstack below.
  */
 
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.word	HEAP_BASE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
diff --git a/nuttx/arch/arm/src/stm32/stm32_allocateheap.c b/nuttx/arch/arm/src/stm32/stm32_allocateheap.c
index 149de8648..6a29fb16c 100644
--- a/nuttx/arch/arm/src/stm32/stm32_allocateheap.c
+++ b/nuttx/arch/arm/src/stm32/stm32_allocateheap.c
@@ -88,7 +88,7 @@
 #endif
 
 /* For the STM312F10xxx family, all internal SRAM is in one contiguous block
- * starting at g_heapbase and extending through CONFIG_DRAM_END (my apologies for
+ * starting at g_idle_topstack and extending through CONFIG_DRAM_END (my apologies for
  * the bad naming).  In addition, external FSMC SRAM may be available.
  */
 
@@ -198,7 +198,7 @@
  *
  * 3)  64Kb of CCM SRAM beginning at address 0x1000:0000
  *
- * As determined by ld.script, g_heapbase lies in the 112Kb memory
+ * As determined by ld.script, g_idle_topstack lies in the 112Kb memory
  * region and that extends to 0x2001:0000.  But the  first and second memory
  * regions are contiguous and treated as one in this logic that extends to
  * 0x2002:0000.
@@ -370,8 +370,8 @@
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
 {
   up_ledon(LED_HEAPALLOCATE);
-  *heap_start = (FAR void*)g_heapbase;
-  *heap_size  = SRAM1_END - g_heapbase;
+  *heap_start = (FAR void*)g_idle_topstack;
+  *heap_size  = SRAM1_END - g_idle_topstack;
 }
 
 /****************************************************************************
diff --git a/nuttx/arch/arm/src/stm32/stm32_vectors.S b/nuttx/arch/arm/src/stm32/stm32_vectors.S
index ab29c2e14..6b9c0affe 100644
--- a/nuttx/arch/arm/src/stm32/stm32_vectors.S
+++ b/nuttx/arch/arm/src/stm32/stm32_vectors.S
@@ -426,14 +426,14 @@ g_intstackbase:
  * and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread is the thread that
  * the system boots on and, eventually, becomes the idle, do nothing task that runs
  * only when there is nothing else to run.  The heap continues from there until the
- * end of memory.  See g_heapbase below.
+ * end of memory.  See g_idle_topstack below.
  */
 
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end
 
diff --git a/nuttx/arch/arm/src/str71x/str71x_head.S b/nuttx/arch/arm/src/str71x/str71x_head.S
index e83affa37..710fd57a5 100644
--- a/nuttx/arch/arm/src/str71x/str71x_head.S
+++ b/nuttx/arch/arm/src/str71x/str71x_head.S
@@ -599,7 +599,7 @@ dtor_end:
 	 * _ebss is the end of the BSS regsion (see ld.script)
 	 * The idle task stack starts at the end of BSS and is
 	 * of size CONFIG_IDLETHREAD_STACKSIZE.  The heap continues
-	 * from there until the end of memory.  See g_heapbase
+	 * from there until the end of memory.  See g_idle_topstack
 	 * below.
 	 */
 
@@ -612,18 +612,18 @@ LC2:	.long	_eronly	/* Where .data defaults are stored in FLASH */
 	.long	_edata
 	.size	__start, .-__start
 
-	/* This global variable is unsigned long g_heapbase and is
+	/* This global variable is unsigned long g_idle_topstack and is
 	 * exported from here only because of its coupling to LCO
 	 * above.
 	 */
 
 	.data
 	.align	4
-	.globl	g_heapbase
-	.type	g_heapbase, object
-g_heapbase:
+	.globl	g_idle_topstack
+	.type	g_idle_topstack, object
+g_idle_topstack:
 	.long	_ebss+CONFIG_IDLETHREAD_STACKSIZE
-	.size	g_heapbase, .-g_heapbase
+	.size	g_idle_topstack, .-g_idle_topstack
 
 	.end