diff --git a/include/l4/generic/resource.h b/include/l4/generic/resource.h
index 0dfb32b..f52e741 100644
--- a/include/l4/generic/resource.h
+++ b/include/l4/generic/resource.h
@@ -98,6 +98,7 @@ struct ktcb *alloc_ktcb(void);
 struct capability *alloc_capability(void);
 struct container *alloc_container(void);
 struct mutex_queue *alloc_user_mutex(void);
+int free_boot_memory(struct kernel_container *kcont);
 
 int init_system_resources(struct kernel_container *kcont);
 
diff --git a/src/api/thread.c b/src/api/thread.c
index ed776bb..a41a929 100644
--- a/src/api/thread.c
+++ b/src/api/thread.c
@@ -249,9 +249,6 @@ int thread_setup_new_ids(struct task_ids *ids, unsigned int flags,
 		new->tgid = new->tid;
 	}
 
-	/* Set all ids */
-	//set_task_ids(new, ids);
-
 	return 0;
 }
 
@@ -354,7 +351,11 @@ out_err:
  */
 int sys_thread_control(unsigned int flags, struct task_ids *ids)
 {
-	int ret = 0;
+	int err, ret = 0;
+
+	if ((err = check_access((unsigned long)ids, sizeof(*ids),
+				MAP_USR_RW_FLAGS, 1)) < 0)
+		return err;
 
 	switch (flags & THREAD_ACTION_MASK) {
 	case THREAD_CREATE:
diff --git a/src/generic/resource.c b/src/generic/resource.c
index 9eba489..db4e8de 100644
--- a/src/generic/resource.c
+++ b/src/generic/resource.c
@@ -161,6 +161,7 @@ int memcap_unmap_range(struct capability *cap,
 	return 0;
 }
 
+
 /*
  * Unmaps given memory range from the list of capabilities
  * by either shrinking, splitting or destroying the
@@ -190,34 +191,56 @@ int memcap_unmap(struct cap_list *cap_list,
 }
 
 /*
- * Migrate any boot allocations to their relevant caches.
+ * TODO: Evaluate if access bits are needed and add new cap ranges
+ * only if their access bits match.
+ *
+ * Maps a memory range as a capability to a list of capabilities either by
+ * merging the given range to an existing capability or creating a new one.
  */
-void migrate_boot_resources(struct boot_resources *bootres,
-			    struct kernel_container *kcont)
+int memcap_map(struct cap_list *cap_list,
+	       const unsigned long map_start,
+	       const unsigned long map_end)
 {
-	/* Migrate boot page tables to new caches */
-	//	migrate_page_tables(kcont);
+	struct capability *cap, *n;
 
-	/* Migrate all boot-allocated capabilities */
-	// migrate_boot_caps(kcont);
+	list_foreach_removable_struct(cap, n, &cap_list->caps, list) {
+		if (cap->start == map_end) {
+			cap->start = map_start;
+			return 0;
+		} else if(cap->end == map_start) {
+			cap->end = map_end;
+			return 0;
+		}
+	}
+
+	/* No capability could be extended, we create a new one */
+	cap = alloc_capability();
+	cap->start = map_start;
+	cap->end = map_end;
+	link_init(&cap->list);
+	cap_list_insert(cap, cap_list);
+
+	return 0;
 }
 
 /* Delete all boot memory and add it to physical memory pool. */
-int free_boot_memory(struct boot_resources *bootres,
-		     struct kernel_container *kcont)
+int free_boot_memory(struct kernel_container *kcont)
 {
+	unsigned long pfn_start =
+		__pfn(virt_to_phys(_start_init));
+	unsigned long pfn_end =
+		__pfn(page_align_up(virt_to_phys(_end_init)));
+
 	/* Trim kernel used memory cap */
-	memcap_unmap(&kcont->physmem_used, (unsigned long)_start_init,
-		     (unsigned long)_end_init);
+	memcap_unmap(&kcont->physmem_used, pfn_start, pfn_end);
 
 	/* Add it to unused physical memory */
-	// memcap_map(&kcont->physmem_free, (unsigned long)_start_init,
-	//	(unsigned long)_end_init);
+	memcap_map(&kcont->physmem_free, pfn_start, pfn_end);
+
+	/* Remove the init memory from the page tables */
+	for (unsigned long i = pfn_start; i < pfn_end; i++)
+		remove_mapping(phys_to_virt(__pfn_to_addr(i)));
 
-       /*
-	* Freed physical area will be unmapped from virtual
-	* by not mapping it in the task page tables.
-	*/
 	return 0;
 }
 
@@ -536,7 +559,7 @@ void init_resource_allocators(struct boot_resources *bootres,
 	kcont->pmd_cache = init_resource_cache(bootres->npmds,
 					       PMD_SIZE, kcont, 1);
 
-	}
+}
 
 /*
  * Do all system accounting for a given capability info
diff --git a/src/glue/arm/init.c b/src/glue/arm/init.c
index db5d6cb..a1b035a 100644
--- a/src/glue/arm/init.c
+++ b/src/glue/arm/init.c
@@ -369,11 +369,6 @@ void setup_dummy_current()
 	TASK_PGD(current) = &init_pgd;
 }
 
-void free_bootmem(void)
-{
-	/* TODO: Fill. */
-}
-
 void init_finalize(struct kernel_container *kcont)
 {
 	volatile register unsigned int stack asm("sp");
@@ -402,7 +397,7 @@ void init_finalize(struct kernel_container *kcont)
 	 * Unmap boot memory, and add it as
 	 * an unused kernel memcap
 	 */
-	free_bootmem();
+	free_boot_memory(&kernel_container);
 
 	/*
 	 * Set up KIP UTCB ref
@@ -444,9 +439,6 @@ void start_kernel(void)
 	remap_as_pages((void *)page_align(_start_kernel),
 		       (void *)page_align_up(_end_kernel));
 
-	/* Move the initial pgd into a more convenient place, mapped as pages. */
-	// relocate_page_tables();
-
 	/* Initialise kip and map for userspace access */
 	kip_init();