diff --git a/defs.h b/defs.h
index 7f1e88d..23b1019 100644
--- a/defs.h
+++ b/defs.h
@@ -74,7 +74,7 @@ void            kbdintr(void);
 int             cpunum(void);
 extern volatile uint*    lapic;
 void            lapiceoi(void);
-void            lapicinit(int);
+void            lapicinit(void);
 void            lapicstartap(uchar, uint);
 void            microdelay(int);
 
@@ -164,7 +164,7 @@ void            uartputc(int);
 void            seginit(void);
 void            kvmalloc(void);
 void            vmenable(void);
-pde_t*          setupkvm();
+pde_t*          setupkvm(void);
 char*           uva2ka(pde_t*, char*);
 int             allocuvm(pde_t*, uint, uint);
 int             deallocuvm(pde_t*, uint, uint);
diff --git a/exec.c b/exec.c
index 312a5c3..a85e203 100644
--- a/exec.c
+++ b/exec.c
@@ -29,7 +29,7 @@ exec(char *path, char **argv)
   if(elf.magic != ELF_MAGIC)
     goto bad;
 
-  if((pgdir = setupkvm(kalloc)) == 0)
+  if((pgdir = setupkvm()) == 0)
     goto bad;
 
   // Load program into memory.
diff --git a/lapic.c b/lapic.c
index effceb1..94b484f 100644
--- a/lapic.c
+++ b/lapic.c
@@ -50,7 +50,7 @@ lapicw(int index, int value)
 //PAGEBREAK!
 
 void
-lapicinit(int c)
+lapicinit(void)
 {
   if(!lapic) 
     return;
diff --git a/main.c b/main.c
index c0c3a91..712958f 100644
--- a/main.c
+++ b/main.c
@@ -20,7 +20,7 @@ main(void)
   kinit1(end, P2V(4*1024*1024)); // phys page allocator
   kvmalloc();      // kernel page table
   mpinit();        // collect info about this machine
-  lapicinit(mpbcpu());
+  lapicinit();
   seginit();       // set up segments
   cprintf("\ncpu%d: starting xv6\n\n", cpu->id);
   picinit();       // interrupt controller
@@ -48,7 +48,7 @@ mpenter(void)
 {
   switchkvm(); 
   seginit();
-  lapicinit(cpunum());
+  lapicinit();
   mpmain();
 }
 
diff --git a/printpcs b/printpcs
new file mode 100755
index 0000000..81d039b
--- /dev/null
+++ b/printpcs
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+# Decode the symbols from a panic EIP list
+
+# Find a working addr2line
+for p in i386-jos-elf-addr2line addr2line; do
+    if which $p 2>&1 >/dev/null && \
+       $p -h 2>&1 | grep -q '\belf32-i386\b'; then
+        break
+    fi
+done
+
+# Enable as much pretty-printing as this addr2line can do
+$p $($p -h | grep ' -[aipsf] ' | awk '{print $1}') -e kernel "$@"
diff --git a/proc.c b/proc.c
index 05cb85f..bcdbfea 100644
--- a/proc.c
+++ b/proc.c
@@ -83,7 +83,7 @@ userinit(void)
   
   p = allocproc();
   initproc = p;
-  if((p->pgdir = setupkvm(kalloc)) == 0)
+  if((p->pgdir = setupkvm()) == 0)
     panic("userinit: out of memory?");
   inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
   p->sz = PGSIZE;
diff --git a/syscall.c b/syscall.c
index 45f758e..799ebc2 100644
--- a/syscall.c
+++ b/syscall.c
@@ -129,9 +129,7 @@ syscall(void)
   int num;
 
   num = proc->tf->eax;
-  if(num >= 0 && num < SYS_open && syscalls[num]) {
-    proc->tf->eax = syscalls[num]();
-  } else if (num >= SYS_open && num < NELEM(syscalls) && syscalls[num]) {
+  if(num > 0 && num < NELEM(syscalls) && syscalls[num]) {
     proc->tf->eax = syscalls[num]();
   } else {
     cprintf("%d %s: unknown sys call %d\n",
diff --git a/syscall.h b/syscall.h
index 59a4576..bc5f356 100644
--- a/syscall.h
+++ b/syscall.h
@@ -13,7 +13,6 @@
 #define SYS_sbrk   12
 #define SYS_sleep  13
 #define SYS_uptime 14
-
 #define SYS_open   15
 #define SYS_write  16
 #define SYS_mknod  17
diff --git a/vm.c b/vm.c
index fa7b706..7cfdc4e 100644
--- a/vm.c
+++ b/vm.c
@@ -118,15 +118,15 @@ static struct kmap {
   uint phys_end;
   int perm;
 } kmap[] = {
-  { (void*) KERNBASE, 0,             EXTMEM,    PTE_W},  // I/O space
-  { (void*) KERNLINK, V2P(KERNLINK), V2P(data), 0}, // kernel text+rodata
-  { (void*) data,     V2P(data),     PHYSTOP,   PTE_W},  // kernel data, memory
-  { (void*) DEVSPACE, DEVSPACE,      0,         PTE_W},  // more devices
+ { (void*)KERNBASE, 0,             EXTMEM,    PTE_W},  // I/O space
+ { (void*)KERNLINK, V2P(KERNLINK), V2P(data), 0},      // kernel text+rodata
+ { (void*)data,     V2P(data),     PHYSTOP,   PTE_W},  // kernel data+memory
+ { (void*)DEVSPACE, DEVSPACE,      0,         PTE_W},  // more devices
 };
 
 // Set up kernel part of a page table.
 pde_t*
-setupkvm()
+setupkvm(void)
 {
   pde_t *pgdir;
   struct kmap *k;