Index: kernel/generic/src/ddi/ddi.c
===================================================================
--- kernel/generic/src/ddi/ddi.c	(revision 482f968b8b53156bb4454e6c369c1e92dc426ea9)
+++ kernel/generic/src/ddi/ddi.c	(revision 3875f1064135338c90e634c95c82359a59d27007)
@@ -49,16 +49,20 @@
 #include <synch/mutex.h>
 #include <syscall/copy.h>
-#include <adt/btree.h>
+#include <adt/odict.h>
 #include <arch.h>
 #include <align.h>
 #include <errno.h>
+#include <mem.h>
 #include <trace.h>
 #include <bitops.h>
 
-/** This lock protects the parea_btree. */
-static mutex_t parea_lock;
-
-/** B+tree with enabled physical memory areas. */
-static btree_t parea_btree;
+/** This lock protects the @c pareas ordered dictionary. */
+static mutex_t pareas_lock;
+
+/** Ordered dictionary of enabled physical memory areas by base address. */
+static odict_t pareas;
+
+static void *pareas_getkey(odlink_t *);
+static int pareas_cmp(void *, void *);
 
 /** Initialize DDI.
@@ -67,6 +71,19 @@
 void ddi_init(void)
 {
-	btree_create(&parea_btree);
-	mutex_initialize(&parea_lock, MUTEX_PASSIVE);
+	odict_initialize(&pareas, pareas_getkey, pareas_cmp);
+	mutex_initialize(&pareas_lock, MUTEX_PASSIVE);
+}
+
+/** Initialize physical area structure.
+ *
+ * This should always be called first on the parea structure before
+ * filling in fields and calling ddi_parea_register.
+ *
+ * @param parea Pointer to physical area structure.
+ *
+ */
+void ddi_parea_init(parea_t *parea)
+{
+	memset(parea, 0, sizeof(parea_t));
 }
 
@@ -78,12 +95,12 @@
 void ddi_parea_register(parea_t *parea)
 {
-	mutex_lock(&parea_lock);
+	mutex_lock(&pareas_lock);
 
 	/*
 	 * We don't check for overlaps here as the kernel is pretty sane.
 	 */
-	btree_insert(&parea_btree, (btree_key_t) parea->pbase, parea, NULL);
-
-	mutex_unlock(&parea_lock);
+	odict_insert(&parea->lpareas, &pareas, NULL);
+
+	mutex_unlock(&pareas_lock);
 }
 
@@ -129,12 +146,12 @@
 	 */
 
-	mutex_lock(&parea_lock);
-	btree_node_t *nodep;
-	parea_t *parea = (parea_t *) btree_search(&parea_btree,
-	    (btree_key_t) phys, &nodep);
+	mutex_lock(&pareas_lock);
+	odlink_t *odlink = odict_find_eq(&pareas, &phys, NULL);
+	parea_t *parea = odlink != NULL ?
+	    odict_get_instance(odlink, parea_t, lpareas) : NULL;
 
 	if ((parea != NULL) && (parea->frames >= pages)) {
 		if ((!priv) && (!parea->unpriv)) {
-			mutex_unlock(&parea_lock);
+			mutex_unlock(&pareas_lock);
 			return EPERM;
 		}
@@ -144,5 +161,5 @@
 
 	parea = NULL;
-	mutex_unlock(&parea_lock);
+	mutex_unlock(&pareas_lock);
 
 	/*
@@ -193,5 +210,5 @@
 
 		if (parea != NULL)
-			mutex_unlock(&parea_lock);
+			mutex_unlock(&pareas_lock);
 
 		return ENOMEM;
@@ -204,5 +221,5 @@
 	if (parea != NULL) {
 		parea->mapped = true;
-		mutex_unlock(&parea_lock);
+		mutex_unlock(&pareas_lock);
 	}
 
@@ -255,4 +272,34 @@
 }
 
+/** Get key function for the @c pareas ordered dictionary.
+ *
+ * @param odlink Link
+ * @return Pointer to base address cast as 'void *'
+ */
+static void *pareas_getkey(odlink_t *odlink)
+{
+	parea_t *parea = odict_get_instance(odlink, parea_t, lpareas);
+	return (void *) &parea->pbase;
+}
+
+/** Key comparison function for the @c pareas ordered dictionary.
+ *
+ * @param a Pointer to parea A base
+ * @param b Pointer to parea B base
+ * @return -1, 0, 1 iff base of A is less than, equal to, greater than B
+ */
+static int pareas_cmp(void *a, void *b)
+{
+	uintptr_t pa = *(uintptr_t *)a;
+	uintptr_t pb = *(uintptr_t *)b;
+
+	if (pa < pb)
+		return -1;
+	else if (pa == pb)
+		return 0;
+	else
+		return +1;
+}
+
 /** Enable range of I/O space for task.
  *
@@ -288,5 +335,5 @@
 	}
 
-	/* Lock the task and release the lock protecting tasks_btree. */
+	/* Lock the task and release the lock protecting tasks dictionary. */
 	irq_spinlock_exchange(&tasks_lock, &task->lock);
 	errno_t rc = ddi_iospace_enable_arch(task, ioaddr, size);
@@ -329,5 +376,5 @@
 	}
 
-	/* Lock the task and release the lock protecting tasks_btree. */
+	/* Lock the task and release the lock protecting tasks dictionary. */
 	irq_spinlock_exchange(&tasks_lock, &task->lock);
 	errno_t rc = ddi_iospace_disable_arch(task, ioaddr, size);