From 2fd3413d350a2c47aeb0bb082577c392060c27d6 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Mon, 1 Sep 2014 07:57:54 -0600
Subject: [PATCH] Fix common heap allocation logic, taking into account the
 kernel build requirements

---
 arch/arm/src/common/up_allocateheap.c | 44 ++++++++++++++++++---------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/arch/arm/src/common/up_allocateheap.c b/arch/arm/src/common/up_allocateheap.c
index f312ae0675..e3443639a1 100644
--- a/arch/arm/src/common/up_allocateheap.c
+++ b/arch/arm/src/common/up_allocateheap.c
@@ -55,13 +55,21 @@
 /****************************************************************************
  * Private Definitions
  ****************************************************************************/
-/* Configuration */
-
-#undef HAVE_KERNEL_HEAP
-#if (defined(CONFIG_BUILD_PROTECTED) || defined(CONFIG_BUILD_KERNEL)) && \
-     defined(CONFIG_MM_KERNEL_HEAP)
-#  define HAVE_KERNEL_HEAP 1
-#endif
+/* Configuration ************************************************************/
+/* Terminology.  In the flat build (CONFIG_BUILD_FLAT=y), there is only a
+ * single heap access with the standard allocations (malloc/free).  This
+ * heap is referred to as the user heap.  In the protected build
+ * (CONFIG_BUILD_PROTECTED=y) where an MPU is used to protect a region of
+ * otherwise flat memory, there will be two allocators:  One that allocates
+ * protected (kernel) memory and one that allocates unprotected (user)
+ * memory.  These are referred to as the kernel and user heaps,
+ * respectively.
+ *
+ * The ARMv7 has no MPU but does have an MMU.  With this MMU, it can support
+ * the kernel build (CONFIG_BUILD_KERNEL=y).  In this configuration, there
+ * is again only one heap but, retaining the terminology, this is the kernel
+ * heap.
+ */
 
 /****************************************************************************
  * Private Data
@@ -76,14 +84,18 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Name: up_allocate_heap
+ * Name: up_allocate_heap/up_allocate_kheap
  *
  * Description:
  *   This function will be called to dynamically set aside the heap region.
  *
- *   For the kernel build (CONFIG_BUILD_KERNEL/PROTECTED=y) with both kernel-
- *   and user-space heaps (CONFIG_MM_KERNEL_HEAP=y), this function provides
- *   the size of the unprotected, user-space heap.
+ *   - For the normal "flat" build, this function returns the size of the
+ *     single heap.
+ *   - For the protected build (CONFIG_BUILD_PROTECTED=y) with both kernel-
+ *     and user-space heaps (CONFIG_MM_KERNEL_HEAP=y), this function
+ *     provides the size of the unprotected, user-space heap.
+ *   - For the kernel build (CONFIG_BUILD_KERNEL=y), this function provides
+ *     the size of the protected, kernel-space heap.
  *
  *   If a protected kernel-space heap is provided, the kernel heap must be
  *   allocated by an analogous up_allocate_kheap(). A custom version of this
@@ -109,9 +121,13 @@
  *
  ****************************************************************************/
 
+#ifdef CONFIG_BUILD_KERNEL
+void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
+#else
 void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
+#endif
 {
-#ifdef HAVE_KERNEL_HEAP
+#if defined(CONFIG_BUILD_PROTECTED) && defined(CONFIG_MM_KERNEL_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).
@@ -143,12 +159,12 @@ void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
  * Description:
  *   For the kernel build (CONFIG_BUILD_PROTECTED/KERNEL=y) with both kernel-
  *   and user-space heaps (CONFIG_MM_KERNEL_HEAP=y), this function allocates
- *   the kernel-space heap.  A custom version of this function is need if
+ *   the kernel-space heap.  A custom version of this function is needed if
  *   memory protection of the kernel heap is required.
  *
  ****************************************************************************/
 
-#ifdef HAVE_KERNEL_HEAP
+#if defined(CONFIG_BUILD_PROTECTED) && defined(CONFIG_MM_KERNEL_HEAP)
 void up_allocate_kheap(FAR void **heap_start, size_t *heap_size)
 {
   /* Get the unaligned size and position of the user-space heap.