diff --git a/bootasm.S b/bootasm.S
index 3cc23e7..c75434b 100644
--- a/bootasm.S
+++ b/bootasm.S
@@ -1,15 +1,12 @@
 #include "asm.h"
+#include "memlayout.h"
+#include "mmu.h"
 
 # Start the first CPU: switch to 32-bit protected mode, jump into C.
 # The BIOS loads this code from the first sector of the hard disk into
 # memory at physical address 0x7c00 and starts executing in real mode
 # with %cs=0 %ip=7c00.
 
-#define SEG_KCODE 1  // kernel code
-#define SEG_KDATA 2  // kernel data+stack
-
-#define CR0_PE    1  // protected mode enable bit
-
 .code16                       # Assemble for 16-bit mode
 .globl start
 start:
@@ -88,3 +85,4 @@ gdt:
 gdtdesc:
   .word   (gdtdesc - gdt - 1)             # sizeof(gdt) - 1
   .long   gdt                             # address gdt
+
diff --git a/bootother.S b/bootother.S
index 2c97207..7b0b815 100644
--- a/bootother.S
+++ b/bootother.S
@@ -1,6 +1,7 @@
 #include "asm.h"
 #include "memlayout.h"
-
+#include "mmu.h"
+	
 # Each non-boot CPU ("AP") is started up in response to a STARTUP
 # IPI from the boot CPU.  Section B.4.2 of the Multi-Processor
 # Specification says that the AP will start in real mode with CS:IP
@@ -20,13 +21,6 @@
 #   - it uses the address at start-4 for the %esp
 #   - it jumps to the address at start-8 instead of calling bootmain
 
-#define SEG_KCODE 1
-#define SEG_KDATA 2
-
-#define CR0_PE    1
-
-#define RELOC1(x) ((x) + KERNBASE)    // same as V2P, but without casts
-
 .code16           
 .globl start
 start:
@@ -56,10 +50,10 @@ start32:
   movw    %ax, %gs
 
   # switch to the stack allocated by bootothers()
-  movl    RELOC1(start-4), %esp
+  movl    P2V_WO(start-4), %esp
 
   # call mpmain()
-  call	*(RELOC1(start)-8)
+  call	*(P2V_WO(start)-8)
 
   movw    $0x8a00, %ax
   movw    %ax, %dx
diff --git a/memlayout.h b/memlayout.h
index 3958062..6c44db2 100644
--- a/memlayout.h
+++ b/memlayout.h
@@ -9,7 +9,7 @@
 #define IOSPACEE  0x100000  // end IO space
 #define PHYSTOP   0xE000000 // use phys mem up to here as free pool
 
-// Key addresses for address space layout (see kmap in vm.c for the actual layout)
+// Key addresses for address space layout (see kmap in vm.c for the layout)
 #define KERNBASE 0xF0000000  // First kernel virtual address
 #define USERTOP  (KERNBASE-PGSIZE)  // Highest user virtual address
 #define KERNLINK 0xF0100000   // Address where kernel is linked
@@ -24,3 +24,5 @@ static inline void *p2v(uint a) { return (void *) a + KERNBASE; }
 #define V2P(a) ((uint) a - KERNBASE)
 #define P2V(a) ((void *) a + KERNBASE)
 
+#define V2P_WO(x) ((x) - KERNBASE)    // same as V2P, but without casts
+#define P2V_WO(x) ((x) + KERNBASE)    // same as V2P, but without casts
diff --git a/mmu.h b/mmu.h
index 86879d2..3e46f41 100644
--- a/mmu.h
+++ b/mmu.h
@@ -37,7 +37,15 @@
 #define CR0_CD		0x40000000	// Cache Disable
 #define CR0_PG		0x80000000	// Paging
 
+#define SEG_KCODE 1  // kernel code
+#define SEG_KDATA 2  // kernel data+stack
+#define SEG_KCPU  3  // kernel per-cpu data
+#define SEG_UCODE 4  // user code
+#define SEG_UDATA 5  // user data+stack
+#define SEG_TSS   6  // this process's task state
+
 //PAGEBREAK!
+#ifndef __ASSEMBLER__
 // Segment Descriptor
 struct segdesc {
   uint lim_15_0 : 16;  // Low bits of segment limit
@@ -64,6 +72,7 @@ struct segdesc {
 { (lim) & 0xffff, (uint)(base) & 0xffff,              \
   ((uint)(base) >> 16) & 0xff, type, 1, dpl, 1,       \
   (uint)(lim) >> 16, 0, 0, 1, 0, (uint)(base) >> 24 }
+#endif
 
 #define DPL_USER    0x3     // User DPL
 
@@ -130,6 +139,7 @@ struct segdesc {
 // Address in page table or page directory entry
 #define PTE_ADDR(pte)	((uint)(pte) & ~0xFFF)
 
+#ifndef __ASSEMBLER__
 typedef uint pte_t;
 
 // Task state segment format
@@ -208,3 +218,4 @@ struct gatedesc {
   (gate).off_31_16 = (uint)(off) >> 16;                  \
 }
 
+#endif
diff --git a/multiboot.S b/multiboot.S
index 84ab638..4aa9f20 100644
--- a/multiboot.S
+++ b/multiboot.S
@@ -16,14 +16,10 @@
 
 #include "asm.h"
 #include "memlayout.h"
-
-#define RELOC(x) ((x) - KERNBASE)    // same as V2P, but without casts
+#include "mmu.h"
 
 #define STACK 4096
 
-#define SEG_KCODE 1  // kernel code
-#define SEG_KDATA 2  // kernel data+stack
-
 # Multiboot header.  Data to direct multiboot loader.
 .p2align 2
 .text
@@ -45,7 +41,7 @@ multiboot_header:
 # boot loader - bootasm.S - sets up.
 .globl multiboot_entry
 multiboot_entry:
-  lgdt RELOC(gdtdesc)
+  lgdt V2P_WO(gdtdesc)
   ljmp $(SEG_KCODE<<3), $mbstart32
 
 mbstart32:
@@ -73,6 +69,6 @@ gdt:
 
 gdtdesc:
   .word   (gdtdesc - gdt - 1)             # sizeof(gdt) - 1
-  .long   RELOC(gdt)                      # address gdt
+  .long   V2P_WO(gdt)                      # address gdt
 
 .comm stack, STACK
diff --git a/proc.h b/proc.h
index 7ffaffb..2b30187 100644
--- a/proc.h
+++ b/proc.h
@@ -1,11 +1,4 @@
 // Segments in proc->gdt.
-// Also known to bootasm.S and trapasm.S
-#define SEG_KCODE 1  // kernel code
-#define SEG_KDATA 2  // kernel data+stack
-#define SEG_KCPU  3  // kernel per-cpu data
-#define SEG_UCODE 4  // user code
-#define SEG_UDATA 5  // user data+stack
-#define SEG_TSS   6  // this process's task state
 #define NSEGS     7
 
 // Per-CPU state
diff --git a/trapasm.S b/trapasm.S
index 1cb2ce6..787727f 100644
--- a/trapasm.S
+++ b/trapasm.S
@@ -1,6 +1,4 @@
-#define SEG_KCODE 1  // kernel code
-#define SEG_KDATA 2  // kernel data+stack
-#define SEG_KCPU  3  // kernel per-cpu data
+#include "mmu.h"
 
   # vectors.S sends all traps here.
 .globl alltraps