diff --git a/conts/libl4/include/l4lib/arch-arm/syscalls.h b/conts/libl4/include/l4lib/arch-arm/syscalls.h
index 584da7a..de08dec 100644
--- a/conts/libl4/include/l4lib/arch-arm/syscalls.h
+++ b/conts/libl4/include/l4lib/arch-arm/syscalls.h
@@ -19,7 +19,6 @@ struct task_ids {
 	l4id_t tid;
 	l4id_t spid;
 	l4id_t tgid;
-	l4id_t cid;
 };
 
 static inline void *
diff --git a/conts/posix/mm0/include/task.h b/conts/posix/mm0/include/task.h
index e5f8f30..b5b8308 100644
--- a/conts/posix/mm0/include/task.h
+++ b/conts/posix/mm0/include/task.h
@@ -96,9 +96,9 @@ struct tcb {
 	char name[16];
 
 	/* Task ids */
-	int tid;
-	int spid;
-	int tgid;
+	l4id_t tid;
+	l4id_t spid;
+	l4id_t tgid;
 
 	/* Related task ids */
 	unsigned int pagerid;		/* Task's pager */
diff --git a/conts/posix/mm0/main.c b/conts/posix/mm0/main.c
index d5514f7..5d98c55 100644
--- a/conts/posix/mm0/main.c
+++ b/conts/posix/mm0/main.c
@@ -195,7 +195,7 @@ void handle_requests(void)
 void main(void)
 {
 
-	printf("\n%s: Started with thread id %d\n", __TASKNAME__, self_tid());
+	printf("\n%s: Started with thread id %x\n", __TASKNAME__, self_tid());
 
 	init();
 
diff --git a/conts/posix/mm0/mm/task.c b/conts/posix/mm0/mm/task.c
index ada721c..b28200f 100644
--- a/conts/posix/mm0/mm/task.c
+++ b/conts/posix/mm0/mm/task.c
@@ -446,7 +446,7 @@ int task_copy_args_to_user(char *user_stack,
 {
 	char **argv_start, **envp_start;
 
-	BUG_ON((unsigned long)user_stack & 7);
+	BUG_ON(!is_aligned(user_stack, 8));
 
 	/* Copy argc */
 	*((int *)user_stack) = args->argc;
@@ -508,12 +508,18 @@ int task_map_stack(struct vm_file *f, struct exec_file_desc *efd,
 		   struct tcb *task, struct args_struct *args,
 		   struct args_struct *env)
 {
-	/* First set up task's stack markers */
-	unsigned long stack_used = align_up(args->size + env->size + 8, 8);
+	unsigned long stack_used;
 	unsigned long arg_pages = __pfn(page_align_up(stack_used));
 	char *args_on_stack;
 	void *mapped;
 
+	/*
+	 * Stack contains: args, environment, argc integer,
+	 * 2 Null integers as terminators.
+	 *
+	 * It needs to be 8-byte aligned also.
+	 */
+	stack_used = align_up(args->size + env->size + sizeof(int) * 3 + 8, 8);
 	task->stack_end = __pfn_to_addr(cont_mem_regions.task->end);
 	task->stack_start = __pfn_to_addr(cont_mem_regions.task->end) - DEFAULT_STACK_SIZE;
 	task->args_end = task->stack_end;
diff --git a/conts/posix/test0/main.c b/conts/posix/test0/main.c
index fdd97b9..51048ff 100644
--- a/conts/posix/test0/main.c
+++ b/conts/posix/test0/main.c
@@ -31,7 +31,7 @@ l4id_t pagerid;
 int main(int argc, char *argv[])
 {
 
-	printf("\n%s: Started with thread id %d\n", __TASKNAME__, getpid());
+	printf("\n%s: Started with thread id %x\n", __TASKNAME__, getpid());
 
 	parent_of_all = getpid();
 
diff --git a/conts/posix/test0/src/test_exec/test_exec.c b/conts/posix/test0/src/test_exec/test_exec.c
index 41695a1..845c512 100644
--- a/conts/posix/test0/src/test_exec/test_exec.c
+++ b/conts/posix/test0/src/test_exec/test_exec.c
@@ -51,7 +51,7 @@ int main(int argc, char *argv[])
 	/* Compare two pid strings. We use strings because we dont have atoi() */
 	if (!strcmp(pidbuf, parent_of_all)) {
 		printf("EXECVE TEST         -- PASSED --\n");
-		printf("\nThread (%d): Continues to sync with the pager...\n\n", getpid());
+		printf("\nThread (%x): Continues to sync with the pager...\n\n", getpid());
 		while (1)
 			wait_pager(pagerid);
 	}
diff --git a/include/l4/generic/container.h b/include/l4/generic/container.h
index f9ac26d..816483e 100644
--- a/include/l4/generic/container.h
+++ b/include/l4/generic/container.h
@@ -107,6 +107,7 @@ int container_init_pagers(struct kernel_resources *kres,
 			  pgd_table_t *current_pgd);
 
 int init_containers(struct kernel_resources *kres);
+struct container *container_find(struct kernel_resources *kres, l4id_t cid);
 
 #endif /* __CONTAINER_H__ */
 
diff --git a/include/l4/generic/resource.h b/include/l4/generic/resource.h
index 8beef1d..6856dc3 100644
--- a/include/l4/generic/resource.h
+++ b/include/l4/generic/resource.h
@@ -32,6 +32,7 @@ struct boot_resources {
 struct container_head {
 	int ncont;
 	struct link list;
+	struct spinlock lock;
 };
 
 static inline void
@@ -39,6 +40,7 @@ container_head_init(struct container_head *chead)
 {
 	chead->ncont = 0;
 	link_init(&chead->list);
+	spin_lock_init(&chead->lock);
 }
 
 /* Hash table for all existing tasks */
diff --git a/include/l4/generic/tcb.h b/include/l4/generic/tcb.h
index ab707d0..787ba09 100644
--- a/include/l4/generic/tcb.h
+++ b/include/l4/generic/tcb.h
@@ -41,6 +41,12 @@ enum task_state {
 
 #define TASK_CID_MASK			0xFF000000
 #define TASK_ID_MASK			0x00FFFFFF
+#define TASK_CID_SHIFT			24
+
+static inline l4id_t tid_to_cid(l4id_t tid)
+{
+	return (tid & TASK_CID_MASK) >> TASK_CID_SHIFT;
+}
 
 static inline int task_id_special(l4id_t id)
 {
@@ -53,7 +59,6 @@ struct task_ids {
 	l4id_t tid;
 	l4id_t spid;
 	l4id_t tgid;
-	l4id_t cid;
 };
 
 struct container;
@@ -166,7 +171,7 @@ void tcb_add(struct ktcb *tcb);
 void tcb_remove(struct ktcb *tcb);
 
 void tcb_init(struct ktcb *tcb);
-struct ktcb *tcb_alloc_init(void);
+struct ktcb *tcb_alloc_init(l4id_t cid);
 void tcb_delete(struct ktcb *tcb);
 
 
diff --git a/src/api/syscall.c b/src/api/syscall.c
index 94fea02..1ff2769 100644
--- a/src/api/syscall.c
+++ b/src/api/syscall.c
@@ -48,7 +48,6 @@ int sys_getid(struct task_ids *ids)
 	ids->tid = this->tid;
 	ids->spid = this->space->spid;
 	ids->tgid = this->tgid;
-	ids->cid = this->container->cid;
 
 	return 0;
 }
diff --git a/src/api/thread.c b/src/api/thread.c
index 5034b4b..618a16d 100644
--- a/src/api/thread.c
+++ b/src/api/thread.c
@@ -346,7 +346,7 @@ int thread_create(struct task_ids *ids, unsigned int flags)
 		}
 	}
 
-	if (!(new = tcb_alloc_init()))
+	if (!(new = tcb_alloc_init(curcont->cid)))
 		return -ENOMEM;
 
 	/* Set up new thread space by using space id and flags */
diff --git a/src/generic/capability.c b/src/generic/capability.c
index a8452f7..ff62991 100644
--- a/src/generic/capability.c
+++ b/src/generic/capability.c
@@ -451,10 +451,11 @@ struct capability *cap_match_thread(struct capability *cap,
 
 	if (action_flags == THREAD_CREATE) {
 		/*
-		 * TODO: Add cid to task_ids arg.
+		 * NOTE: Currently we only allow creation in
+		 * current container.
 		 *
-		 * Its a thread create and we have no knowledge of
-		 * thread id, space id, or any other id.
+		 * TODO: Add capability checking for space,
+		 * as well.
 		 *
 		 * We _assume_ target is the largest group,
 		 * e.g. same container as current. We check
@@ -462,7 +463,7 @@ struct capability *cap_match_thread(struct capability *cap,
 		 */
 		if (cap_rtype(cap) != CAP_RTYPE_CONTAINER)
 			return 0;
-		if (cap->resid != current->container->cid)
+		if (cap->resid != curcont->cid)
 			return 0;
 		/* Resource type and id match, success */
 		return cap;
diff --git a/src/generic/container.c b/src/generic/container.c
index 3a447f8..8f248ad 100644
--- a/src/generic/container.c
+++ b/src/generic/container.c
@@ -47,8 +47,25 @@ struct container *container_create(void)
 void kres_insert_container(struct container *c,
 			    struct kernel_resources *kres)
 {
+	spin_lock(&kres->containers.lock);
 	list_insert(&c->list, &kres->containers.list);
 	kres->containers.ncont++;
+	spin_unlock(&kres->containers.lock);
+}
+
+struct container *container_find(struct kernel_resources *kres, l4id_t cid)
+{
+	struct container *c;
+
+	spin_lock(&kres->containers.lock);
+	list_foreach_struct(c, &kres->containers.list, list) {
+		if (c->cid == cid) {
+			spin_unlock(&kres->containers.lock);
+			return c;
+		}
+	}
+	spin_unlock(&kres->containers.lock);
+	return 0;
 }
 
 /*
@@ -86,8 +103,11 @@ int init_pager(struct pager *pager,
 	 */
 	cap_list_move(&current->cap_list, &pager->cap_list);
 
+	/* Setup dummy container pointer so that curcont works */
+	current->container = cont;
+
 	/* New ktcb allocation is needed */
-	task = tcb_alloc_init();
+	task = tcb_alloc_init(cont->cid);
 
 	/* If first, manually allocate/initalize space */
 	if (first) {
@@ -117,11 +137,7 @@ int init_pager(struct pager *pager,
 	task->tgid = task->tid;
 	task->container = cont;
 
-	/*
-	 * Setup dummy container pointer so that curcont works,
-	 * and add the address space to container space list
-	 */
-	current->container = cont;
+	/* Add the address space to container space list */
 	address_space_add(task->space);
 
 	/* Initialize uninitialized capability fields while on dummy */
diff --git a/src/generic/resource.c b/src/generic/resource.c
index 4ec4318..705cf78 100644
--- a/src/generic/resource.c
+++ b/src/generic/resource.c
@@ -402,8 +402,6 @@ void init_kernel_resources(struct kernel_resources *kres)
 	memcap_unmap(&kres->physmem_free, kernel_area->start,
 		     kernel_area->end);
 
-	/* Initialize zombie pager list */
-	init_ktcb_list(&kres->zombie_list);
 
 	/* TODO:
 	 * Add all virtual memory areas used by the kernel
@@ -529,7 +527,8 @@ void setup_kernel_resources(struct boot_resources *bootres,
 	 * See how many containers we have. Assign next
 	 * unused container id for kernel resources
 	 */
-	kres->cid = id_get(&kres->container_ids, bootres->nconts + 1);
+	//kres->cid = id_get(&kres->container_ids, bootres->nconts + 1);
+	kres->cid = id_get(&kres->container_ids, 0);
 
 	/* First initialize the list of non-memory capabilities */
 	cap = boot_capability_create();
diff --git a/src/generic/tcb.c b/src/generic/tcb.c
index 47dcab4..dce4b47 100644
--- a/src/generic/tcb.c
+++ b/src/generic/tcb.c
@@ -43,7 +43,7 @@ void tcb_init(struct ktcb *new)
 	waitqueue_head_init(&new->wqh_pager);
 }
 
-struct ktcb *tcb_alloc_init(void)
+struct ktcb *tcb_alloc_init(l4id_t cid)
 {
 	struct ktcb *tcb;
 	struct task_ids ids;
@@ -52,6 +52,7 @@ struct ktcb *tcb_alloc_init(void)
 		return 0;
 
 	ids.tid = id_new(&kernel_resources.ktcb_ids);
+	ids.tid |= TASK_CID_MASK & (cid << TASK_CID_SHIFT);
 	ids.tgid = L4_NILTHREAD;
 	ids.spid = L4_NILTHREAD;
 
@@ -92,6 +93,9 @@ void tcb_delete(struct ktcb *tcb)
 		mutex_unlock(&curcont->space_list.lock);
 	}
 
+	/* Clear container id part */
+	tcb->tid &= ~TASK_CID_MASK;
+
 	/* Deallocate tcb ids */
 	id_del(&kernel_resources.ktcb_ids, tcb->tid);
 
@@ -114,22 +118,44 @@ struct ktcb *tcb_find_by_space(l4id_t spid)
 	return 0;
 }
 
-struct ktcb *tcb_find(l4id_t tid)
+struct ktcb *container_find_tcb(struct container *c, l4id_t tid)
 {
 	struct ktcb *task;
 
+	spin_lock(&c->ktcb_list.list_lock);
+	list_foreach_struct(task, &c->ktcb_list.list, task_list) {
+		if (task->tid == tid) {
+			spin_unlock(&c->ktcb_list.list_lock);
+			return task;
+		}
+	}
+	spin_unlock(&c->ktcb_list.list_lock);
+	return 0;
+}
+
+/*
+ * Threads are the only resource where inter-container searches are
+ * allowed. This is because on other containers, only threads can be
+ * targeted for operations. E.g. ipc, sharing memory. Currently you
+ * can't reach a space, a mutex, or any other resouce on another
+ * container.
+ */
+struct ktcb *tcb_find(l4id_t tid)
+{
+	struct container *c;
+
 	if (current->tid == tid)
 		return current;
 
-	spin_lock(&curcont->ktcb_list.list_lock);
-	list_foreach_struct(task, &curcont->ktcb_list.list, task_list) {
-		if (task->tid == tid) {
-			spin_unlock(&curcont->ktcb_list.list_lock);
-			return task;
-		}
+	if (tid_to_cid(tid) == curcont->cid) {
+		return container_find_tcb(curcont, tid);
+	} else {
+	       	if (!(c = container_find(&kernel_resources,
+					 tid_to_cid(tid))))
+			return 0;
+		else
+			return container_find_tcb(c, tid);
 	}
-	spin_unlock(&curcont->ktcb_list.list_lock);
-	return 0;
 }
 
 void ktcb_list_add(struct ktcb *new, struct ktcb_list *ktcb_list)