diff --git a/kernel/src/objects/cap.rs b/kernel/src/objects/cap.rs
index fe12c9b..47ff0d6 100644
--- a/kernel/src/objects/cap.rs
+++ b/kernel/src/objects/cap.rs
@@ -21,8 +21,6 @@ pub struct RawCap {
     pub ptr:      PhysAddr,
     /// cap_type: every capability links to one specific object
     pub cap_type: ObjectType,
-    /// _padding: padding to align the size of RawCap to power of 2
-    pub _padding: [usize; 2],
 }
 
 impl RawCap {
@@ -31,7 +29,6 @@ impl RawCap {
             args: [arg0, arg1],
             ptr,
             cap_type,
-            _padding: [0, 0],
         }
     }
 }
@@ -43,8 +40,6 @@ pub struct CapEntry {
 
 LinkHelperImpl!(CapEntry: link);
 
-const_assert_eq!(core::mem::size_of::<CapEntry>(), ObjectType::CNode.size(0));
-
 impl CapEntry {
     pub fn new(cap: RawCap) -> Self {
         Self {
diff --git a/kernel/src/objects/cnode.rs b/kernel/src/objects/cnode.rs
index 777e9d2..0217469 100644
--- a/kernel/src/objects/cnode.rs
+++ b/kernel/src/objects/cnode.rs
@@ -12,6 +12,8 @@ use utils::MASK;
 /// The size of the array is stored in CNodeCap
 pub type CNodeObject = [CapEntry];
 
+const_assert!(core::mem::size_of::<CapEntry>() <= ObjectType::CNode.size(0));
+
 impl KernelObject for CNodeObject {
     const OBJ_TYPE: ObjectType = ObjectType::CNode;
 }
@@ -157,11 +159,11 @@ mod tests {
 
     #[test_case]
     fn test_cnode_resolve() {
-        let create_cnode = |radix: usize, guard_size: usize, guard: usize| {
-            let size = ObjectType::CNode.size(radix);
+        let create_cnode = |radix_bits: usize, guard_bits: usize, guard: usize| {
+            let size = ObjectType::CNode.size(radix_bits);
             let layout = Layout::from_size_align(size, 1).unwrap();
             let ptr = RAM_ALLOCATOR.lock().alloc(layout).unwrap();
-            let raw = CNodeCap::mint(radix, guard_size, guard, ptr);
+            let raw = CNodeCap::mint(radix_bits, guard_bits, guard, ptr);
             CapEntry::new(raw)
         };
 
diff --git a/kernel/src/objects/table.rs b/kernel/src/objects/table.rs
index ca4cb22..f1a89c3 100644
--- a/kernel/src/objects/table.rs
+++ b/kernel/src/objects/table.rs
@@ -8,7 +8,7 @@ use uapi::{
 use utils::{addr::*, MASK};
 
 /// TableObject is an object that represents a page table
-pub struct TableObject([usize]);
+pub struct TableObject([u8]);
 impl KernelObject for TableObject {
     const OBJ_TYPE: ObjectType = ObjectType::PageTable;
 }
diff --git a/kernel/src/objects/tcb.rs b/kernel/src/objects/tcb.rs
index b83a692..affdb46 100644
--- a/kernel/src/objects/tcb.rs
+++ b/kernel/src/objects/tcb.rs
@@ -43,6 +43,9 @@ pub struct TcbObject {
 
 LinkHelperImpl!(TcbObject:link);
 
+const_assert_eq!(ObjectType::TCB.size(0), ObjectType::TCB.size(0x42));
+const_assert!(core::mem::size_of::<TcbObject>() <= ObjectType::TCB.size(0));
+
 impl TcbObject {
     pub fn new() -> Self {
         Self {
diff --git a/uapi/src/cap.rs b/uapi/src/cap.rs
index c0a4764..912f3f3 100644
--- a/uapi/src/cap.rs
+++ b/uapi/src/cap.rs
@@ -3,14 +3,13 @@ pub enum ObjectType {
     Null         = 0,
     CNode        = 1,
     TCB          = 2,
-    SchedCtx     = 3,
-    Endpoint     = 4,
-    Reply        = 5,
-    Notification = 6,
-    Frame        = 7,
-    PageTable    = 8,
-    Interrupt    = 9,
-    Untyped      = 10,
+    Endpoint     = 3,
+    Reply        = 4,
+    Notification = 5,
+    Frame        = 6,
+    PageTable    = 7,
+    Interrupt    = 8,
+    Untyped      = 9,
 }
 
 impl Default for ObjectType {
@@ -20,7 +19,8 @@ impl Default for ObjectType {
 }
 
 impl ObjectType {
-    const CNODE_BITS: usize = 6;
+    const CNODE_BITS: usize = 6; // 48 bytes
+    const TCB_BITS: usize = 10; // 672 bytes
 
     pub const fn size(&self, user_obj_bits: usize) -> usize {
         1 << self.bits(user_obj_bits)
@@ -29,15 +29,14 @@ impl ObjectType {
     pub const fn bits(&self, user_obj_bits: usize) -> usize {
         #![rustfmt::skip]
         match self {
-            ObjectType::Null         => 0, // TODO: fill it!
+            ObjectType::Null         => 0,
             ObjectType::CNode        => Self::CNODE_BITS + user_obj_bits,
-            ObjectType::TCB          => 0, // TODO: fill it!
-            ObjectType::SchedCtx     => 0, // TODO: fill it!
+            ObjectType::TCB          => Self::TCB_BITS,
             ObjectType::Endpoint     => 0, // TODO: fill it!
             ObjectType::Reply        => 0, // TODO: fill it!
             ObjectType::Notification => 0, // TODO: fill it!
-            ObjectType::Frame        => 0, // TODO: fill it!
-            ObjectType::PageTable    => 0, // TODO: fill it!
+            ObjectType::Frame        => user_obj_bits,
+            ObjectType::PageTable    => user_obj_bits, // arch dependent page table size
             ObjectType::Interrupt    => 0, // TODO: fill it!
             ObjectType::Untyped      => user_obj_bits,
         }