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diff --git a/kern/rdxtree.h b/kern/rdxtree.h
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+/*
+ * Copyright (c) 2011-2015 Richard Braun.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *
+ * Radix tree.
+ *
+ * In addition to the standard insertion operation, this implementation
+ * can allocate keys for the caller at insertion time.
+ *
+ * Upstream site with license notes :
+ * http://git.sceen.net/rbraun/librbraun.git/
+ */
+
+#ifndef _RDXTREE_H
+#define _RDXTREE_H
+
+#include <stddef.h>
+#include <sys/types.h>
+
+/*
+ * Initialize the node cache.
+ */
+void rdxtree_cache_init(void);
+
+/*
+ * This macro selects between 32 or 64-bits (the default) keys.
+ */
+#if 0
+#define RDXTREE_KEY_32
+#endif
+
+#ifdef RDXTREE_KEY_32
+typedef uint32_t rdxtree_key_t;
+#else /* RDXTREE_KEY_32 */
+typedef uint64_t rdxtree_key_t;
+#endif /* RDXTREE_KEY_32 */
+
+/*
+ * Radix tree.
+ */
+struct rdxtree;
+
+/*
+ * Radix tree iterator.
+ */
+struct rdxtree_iter;
+
+/*
+ * Static tree initializer.
+ */
+#define RDXTREE_INITIALIZER { 0, NULL }
+
+#include "rdxtree_i.h"
+
+/*
+ * Initialize a tree.
+ */
+static inline void
+rdxtree_init(struct rdxtree *tree)
+{
+    tree->height = 0;
+    tree->root = NULL;
+}
+
+/*
+ * Insert a pointer in a tree.
+ *
+ * The ptr parameter must not be NULL.
+ */
+static inline int
+rdxtree_insert(struct rdxtree *tree, rdxtree_key_t key, void *ptr)
+{
+    return rdxtree_insert_common(tree, key, ptr, NULL);
+}
+
+/*
+ * Insert a pointer in a tree and obtain its slot.
+ *
+ * The ptr and slotp parameters must not be NULL. If successful, the slot of
+ * the newly inserted pointer is stored at the address pointed to by the slotp
+ * parameter.
+ */
+static inline int
+rdxtree_insert_slot(struct rdxtree *tree, rdxtree_key_t key,
+                    void *ptr, void ***slotp)
+{
+    return rdxtree_insert_common(tree, key, ptr, slotp);
+}
+
+/*
+ * Insert a pointer in a tree, for which a new key is allocated.
+ *
+ * The ptr and keyp parameters must not be NULL. The newly allocated key is
+ * stored at the address pointed to by the keyp parameter.
+ */
+static inline int
+rdxtree_insert_alloc(struct rdxtree *tree, void *ptr, rdxtree_key_t *keyp)
+{
+    return rdxtree_insert_alloc_common(tree, ptr, keyp, NULL);
+}
+
+/*
+ * Insert a pointer in a tree, for which a new key is allocated, and obtain
+ * its slot.
+ *
+ * The ptr, keyp and slotp parameters must not be NULL. The newly allocated
+ * key is stored at the address pointed to by the keyp parameter while the
+ * slot of the inserted pointer is stored at the address pointed to by the
+ * slotp parameter.
+ */
+static inline int
+rdxtree_insert_alloc_slot(struct rdxtree *tree, void *ptr,
+                          rdxtree_key_t *keyp, void ***slotp)
+{
+    return rdxtree_insert_alloc_common(tree, ptr, keyp, slotp);
+}
+
+/*
+ * Remove a pointer from a tree.
+ *
+ * The matching pointer is returned if successful, NULL otherwise.
+ */
+void * rdxtree_remove(struct rdxtree *tree, rdxtree_key_t key);
+
+/*
+ * Look up a pointer in a tree.
+ *
+ * The matching pointer is returned if successful, NULL otherwise.
+ */
+static inline void *
+rdxtree_lookup(const struct rdxtree *tree, rdxtree_key_t key)
+{
+    return rdxtree_lookup_common(tree, key, 0);
+}
+
+/*
+ * Look up a slot in a tree.
+ *
+ * A slot is a pointer to a stored pointer in a tree. It can be used as
+ * a placeholder for fast replacements to avoid multiple lookups on the same
+ * key.
+ *
+ * A slot for the matching pointer is returned if successful, NULL otherwise.
+ *
+ * See rdxtree_replace_slot().
+ */
+static inline void **
+rdxtree_lookup_slot(const struct rdxtree *tree, rdxtree_key_t key)
+{
+    return rdxtree_lookup_common(tree, key, 1);
+}
+
+/*
+ * Replace a pointer in a tree.
+ *
+ * The ptr parameter must not be NULL. The previous pointer is returned.
+ *
+ * See rdxtree_lookup_slot().
+ */
+void * rdxtree_replace_slot(void **slot, void *ptr);
+
+/*
+ * Forge a loop to process all pointers of a tree.
+ */
+#define rdxtree_for_each(tree, iter, ptr)                       \
+for (rdxtree_iter_init(iter), ptr = rdxtree_walk(tree, iter);   \
+     ptr != NULL;                                               \
+     ptr = rdxtree_walk(tree, iter))
+
+/*
+ * Return the key of the current pointer from an iterator.
+ */
+static inline rdxtree_key_t
+rdxtree_iter_key(const struct rdxtree_iter *iter)
+{
+    return iter->key;
+}
+
+/*
+ * Remove all pointers from a tree.
+ *
+ * The common way to destroy a tree and its pointers is to loop over all
+ * the pointers using rdxtree_for_each(), freeing them, then call this
+ * function.
+ */
+void rdxtree_remove_all(struct rdxtree *tree);
+
+#endif /* _RDXTREE_H */