shuffle and tweak for formatting.

pdf has very good page breaks now. would be a good copy for fall 2009.

shuffle and tweak for formatting.
0aef8914 · Russ Cox · b3bebfce · 0aef8914 · 0aef8914 · 0aef8914
--- a/Makefile
+++ b/Makefile
@@ -128,6 +128,7 @@ PRINT = runoff.list $(FILES)
 xv6.pdf: $(PRINT)
 	./runoff
+	ls -l xv6.pdf
 print: xv6.pdf

--- a/bootother.S
+++ b/bootother.S
@@ -38,7 +38,7 @@ start:
 //PAGEBREAK!
  # Switch from real to protected mode, using a bootstrap GDT
  # and segment translation that makes virtual addresses 
-  # identical to their physical addresses, so that the 
+  # identical to physical addresses, so that the 
  # effective memory map does not change during the switch.
  lgdt    gdtdesc
  movl    %cr0, %eax
@@ -47,10 +47,10 @@ start:
  # Jump to next instruction, but in 32-bit code segment.
  # Switches processor into 32-bit mode.
-  ljmp    $(SEG_KCODE<<3), $protcseg
+  ljmp    $(SEG_KCODE<<3), $start32
-  .code32                     # Assemble for 32-bit mode
+.code32                       # Assemble for 32-bit mode
-protcseg:
+start32:
  # Set up the protected-mode data segment registers
  movw    $(SEG_KDATA<<3), %ax    # Our data segment selector
  movw    %ax, %ds                # -> DS: Data Segment
@@ -60,11 +60,11 @@ protcseg:
  movw    %ax, %fs                # -> FS
  movw    %ax, %gs                # -> GS
+  # Set up the stack pointer and call into C.
  movl    start-4, %esp
-  movl    start-8, %eax
+  call	*(start-8)
-  call    *%eax
-  # If bootmain returns (it shouldn't), trigger a Bochs
+  # If the call returns (it shouldn't), trigger a Bochs
  # breakpoint if running under Bochs, then loop.
  movw    $0x8a00, %ax            # 0x8a00 -> port 0x8a00
  movw    %ax, %dx

--- a/console.c
+++ b/console.c
@@ -7,69 +7,22 @@
 #include "param.h"
 #include "traps.h"
 #include "spinlock.h"
-#include "dev.h"
+#include "fs.h"
+#include "file.h"
 #include "mmu.h"
 #include "proc.h"
 #include "x86.h"
-#define CRTPORT 0x3d4
+static void consputc(int);
-#define BACKSPACE 0x100
-static ushort *crt = (ushort*)0xb8000;  // CGA memory
+static int panicked = 0;
 static struct {
 	struct spinlock lock;
 	int locking;
 } cons;
-static int panicked = 0;
 static void
-cgaputc(int c)
-{
-  int pos;
-  // Cursor position: col + 80*row.
-  outb(CRTPORT, 14);
-  pos = inb(CRTPORT+1) << 8;
-  outb(CRTPORT, 15);
-  pos |= inb(CRTPORT+1);
-  if(c == '\n')
-    pos += 80 - pos%80;
-  else if(c == BACKSPACE){
-    if(pos > 0)
-      crt[--pos] = ' ' | 0x0700;
-  } else
-    crt[pos++] = (c&0xff) | 0x0700;  // black on white
-  if((pos/80) >= 24){  // Scroll up.
-    memmove(crt, crt+80, sizeof(crt[0])*23*80);
-    pos -= 80;
-    memset(crt+pos, 0, sizeof(crt[0])*(24*80 - pos));
-  }
-  outb(CRTPORT, 14);
-  outb(CRTPORT+1, pos>>8);
-  outb(CRTPORT, 15);
-  outb(CRTPORT+1, pos);
-  crt[pos] = ' ' | 0x0700;
-}
-void
-consputc(int c)
-{
-  if(panicked){
-    cli();
-    for(;;)
-      ;
-  }
-  uartputc(c);
-  cgaputc(c);
-}
-void
 printint(int xx, int base, int sgn)
 {
  static char digits[] = "0123456789abcdef";
@@ -79,10 +32,9 @@ printint(int xx, int base, int sgn)
  if(sgn && xx < 0){
    neg = 1;
-    x = 0 - xx;
+    x = -xx;
-  } else {
+  } else
    x = xx;
-  }
  do{
    buf[i++] = digits[x % base];
@@ -94,6 +46,7 @@ printint(int xx, int base, int sgn)
    consputc(buf[i]);
 }
+//PAGEBREAK: 50
 // Print to the console. only understands %d, %x, %p, %s.
 void
 cprintf(char *fmt, ...)
@@ -108,17 +61,14 @@ cprintf(char *fmt, ...)
  argp = (uint*)(void*)&fmt + 1;
  state = 0;
-  for(i = 0; fmt[i]; i++){
+  for(i = 0; (c = fmt[i] & 0xff) != 0; i++){
-    c = fmt[i] & 0xff;
+    if(c != '%'){
-    switch(state){
-    case 0:
-      if(c == '%')
-        state = '%';
-      else
      consputc(c);
+      continue;
+    }
+    c = fmt[++i] & 0xff;
+    if(c == 0)
      break;
-    case '%':
    switch(c){
    case 'd':
      printint(*argp++, 10, 1);
@@ -128,8 +78,7 @@ cprintf(char *fmt, ...)
      printint(*argp++, 16, 0);
      break;
    case 's':
-        s = (char*)*argp++;
+      if((s = (char*)*argp++) == 0)
-        if(s == 0)
        s = "(null)";
      for(; *s; s++)
        consputc(*s);
@@ -143,30 +92,82 @@ cprintf(char *fmt, ...)
      consputc(c);
      break;
    }
-      state = 0;
-      break;
-    }
  }
  if(locking)
    release(&cons.lock);
 }
-int
+void
-consolewrite(struct inode *ip, char *buf, int n)
+panic(char *s)
 {
  int i;
+  uint pcs[10];
-  iunlock(ip);
+  cli();
-  acquire(&cons.lock);
+  cons.locking = 0;
-  for(i = 0; i < n; i++)
+  cprintf("cpu%d: panic: ", cpu());
-    consputc(buf[i] & 0xff);
+  cprintf(s);
-  release(&cons.lock);
+  cprintf("\n");
-  ilock(ip);
+  getcallerpcs(&s, pcs);
+  for(i=0; i<10; i++)
+    cprintf(" %p", pcs[i]);
+  panicked = 1; // freeze other CPU
+  for(;;)
+    ;
+}
-  return n;
+//PAGEBREAK: 50
+#define BACKSPACE 0x100
+#define CRTPORT 0x3d4
+static ushort *crt = (ushort*)0xb8000;  // CGA memory
+static void
+cgaputc(int c)
+{
+  int pos;
+  // Cursor position: col + 80*row.
+  outb(CRTPORT, 14);
+  pos = inb(CRTPORT+1) << 8;
+  outb(CRTPORT, 15);
+  pos |= inb(CRTPORT+1);
+  if(c == '\n')
+    pos += 80 - pos%80;
+  else if(c == BACKSPACE){
+    if(pos > 0)
+      crt[--pos] = ' ' | 0x0700;
+  } else
+    crt[pos++] = (c&0xff) | 0x0700;  // black on white
+  if((pos/80) >= 24){  // Scroll up.
+    memmove(crt, crt+80, sizeof(crt[0])*23*80);
+    pos -= 80;
+    memset(crt+pos, 0, sizeof(crt[0])*(24*80 - pos));
+  }
+  outb(CRTPORT, 14);
+  outb(CRTPORT+1, pos>>8);
+  outb(CRTPORT, 15);
+  outb(CRTPORT+1, pos);
+  crt[pos] = ' ' | 0x0700;
+}
+void
+consputc(int c)
+{
+  if(panicked){
+    cli();
+    for(;;)
+      ;
+  }
+  uartputc(c);
+  cgaputc(c);
 }
+//PAGEBREAK: 50
 #define INPUT_BUF 128
 struct {
  struct spinlock lock;
@@ -255,6 +256,21 @@ consoleread(struct inode *ip, char *dst, int n)
  return target - n;
 }
+int
+consolewrite(struct inode *ip, char *buf, int n)
+{
+  int i;
+  iunlock(ip);
+  acquire(&cons.lock);
+  for(i = 0; i < n; i++)
+    consputc(buf[i] & 0xff);
+  release(&cons.lock);
+  ilock(ip);
+  return n;
+}
 void
 consoleinit(void)
 {
@@ -269,22 +285,3 @@ consoleinit(void)
  ioapicenable(IRQ_KBD, 0);
 }
-void
-panic(char *s)
-{
-  int i;
-  uint pcs[10];
-  cli();
-  cons.locking = 0;
-  cprintf("cpu%d: panic: ", cpu());
-  cprintf(s);
-  cprintf("\n");
-  getcallerpcs(&s, pcs);
-  for(i=0; i<10; i++)
-    cprintf(" %p", pcs[i]);
-  panicked = 1; // freeze other CPU
-  for(;;)
-    ;
-}
--- a/defs.h
+++ b/defs.h
@@ -91,6 +91,7 @@ void            pipeclose(struct pipe*, int);
 int             piperead(struct pipe*, char*, int);
 int             pipewrite(struct pipe*, char*, int);
+//PAGEBREAK: 16
 // proc.c
 struct proc*    copyproc(struct proc*);
 void            exit(void);

--- a/dev.h
+++ b/dev.h
-struct devsw {
-  int (*read)(struct inode*, char*, int);
-  int (*write)(struct inode*, char*, int);
-};
-extern struct devsw devsw[];
-#define CONSOLE 1
--- a/elf.h
+++ b/elf.h
@@ -40,21 +40,3 @@ struct proghdr {
 #define ELF_PROG_FLAG_EXEC      1
 #define ELF_PROG_FLAG_WRITE     2
 #define ELF_PROG_FLAG_READ      4
-// Blank page.
--- a/exec.c
+++ b/exec.c
@@ -11,7 +11,7 @@ exec(char *path, char **argv)
 {
  char *mem, *s, *last;
  int i, argc, arglen, len, off;
-  uint sz, sp, argp;
+  uint sz, sp, argp, x;
  struct elfhdr elf;
  struct inode *ip;
  struct proghdr ph;
@@ -67,7 +67,9 @@ exec(char *path, char **argv)
      goto bad;
    if(ph.type != ELF_PROG_LOAD)
      continue;
-    if(ph.va + ph.memsz < ph.va || ph.va + ph.memsz > sz || ph.memsz < ph.filesz)
+    if(ph.va + ph.memsz < ph.va || ph.va + ph.memsz > sz)
+      goto bad;
+    if(ph.memsz < ph.filesz)
      goto bad;
    if(readi(ip, mem + ph.va, ph.offset, ph.filesz) != ph.filesz)
      goto bad;

--- a/file.c
+++ b/file.c
 #include "types.h"
 #include "defs.h"
 #include "param.h"
+#include "fs.h"
 #include "file.h"
 #include "spinlock.h"
-#include "dev.h"
 struct devsw devsw[NDEV];
 struct {

--- a/file.h
+++ b/file.h
@@ -7,3 +7,35 @@ struct file {
  struct inode *ip;
  uint off;
 };
+// in-core file system types
+struct inode {
+  uint dev;           // Device number
+  uint inum;          // Inode number
+  int ref;            // Reference count
+  int flags;          // I_BUSY, I_VALID
+  short type;         // copy of disk inode
+  short major;
+  short minor;
+  short nlink;
+  uint size;
+  uint addrs[NDIRECT+1];
+};
+#define I_BUSY 0x1
+#define I_VALID 0x2
+// device implementations
+struct devsw {
+  int (*read)(struct inode*, char*, int);
+  int (*write)(struct inode*, char*, int);
+};
+extern struct devsw devsw[];
+#define CONSOLE 1
--- a/fs.c
+++ b/fs.c
@@ -19,8 +19,7 @@
 #include "spinlock.h"
 #include "buf.h"
 #include "fs.h"
-#include "fsvar.h"
+#include "file.h"
-#include "dev.h"
 #define min(a, b) ((a) < (b) ? (a) : (b))
 static void itrunc(struct inode*);

--- a/fsvar.h
+++ b/fsvar.h
-// in-core file system types
-struct inode {
-  uint dev;           // Device number
-  uint inum;          // Inode number
-  int ref;            // Reference count
-  int flags;          // I_BUSY, I_VALID
-  short type;         // copy of disk inode
-  short major;
-  short minor;
-  short nlink;
-  uint size;
-  uint addrs[NDIRECT+1];
-};
-#define I_BUSY 0x1
-#define I_VALID 0x2
--- a/picirq.c
+++ b/picirq.c
@@ -82,3 +82,32 @@ picinit(void)
  if(irqmask != 0xFFFF)
    picsetmask(irqmask);
 }
+// Blank page.
--- a/pipe.c
+++ b/pipe.c
@@ -3,6 +3,7 @@
 #include "param.h"
 #include "mmu.h"
 #include "proc.h"
+#include "fs.h"
 #include "file.h"
 #include "spinlock.h"
@@ -72,7 +73,7 @@ pipeclose(struct pipe *p, int writable)
    release(&p->lock);
 }
-//PAGEBREAK: 30
+//PAGEBREAK: 40
 int
 pipewrite(struct pipe *p, char *addr, int n)
 {

--- a/proc.c
+++ b/proc.c
@@ -23,6 +23,79 @@ pinit(void)
  initlock(&ptable.lock, "ptable");
 }
+//PAGEBREAK: 36
+// Print a process listing to console.  For debugging.
+// Runs when user types ^P on console.
+// No lock to avoid wedging a stuck machine further.
+void
+procdump(void)
+{
+  static char *states[] = {
+  [UNUSED]    "unused",
+  [EMBRYO]    "embryo",
+  [SLEEPING]  "sleep ",
+  [RUNNABLE]  "runble",
+  [RUNNING]   "run   ",
+  [ZOMBIE]    "zombie"
+  };
+  int i;
+  struct proc *p;
+  char *state;
+  uint pc[10];
+  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
+    if(p->state == UNUSED)
+      continue;
+    if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
+      state = states[p->state];
+    else
+      state = "???";
+    cprintf("%d %s %s", p->pid, state, p->name);
+    if(p->state == SLEEPING){
+      getcallerpcs((uint*)p->context->ebp+2, pc);
+      for(i=0; i<10 && pc[i] != 0; i++)
+        cprintf(" %p", pc[i]);
+    }
+    cprintf("\n");
+  }
+}
+// Set up CPU's kernel segment descriptors.
+// Run once at boot time on each CPU.
+void
+ksegment(void)
+{
+  struct cpu *c1;
+  c1 = &cpus[cpu()];
+  c1->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
+  c1->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
+  c1->gdt[SEG_KCPU] = SEG(STA_W, (uint)(&c1->tls+1), 0xffffffff, 0);
+  lgdt(c1->gdt, sizeof(c1->gdt));
+  loadfsgs(SEG_KCPU << 3);
+  // Initialize cpu-local variables.
+  c = c1;
+  cp = 0;
+}
+// Set up CPU's segment descriptors and current process task state.
+// If cp==0, set up for "idle" state for when scheduler() is running.
+void
+usegment(void)
+{
+  pushcli();
+  c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)cp->mem, cp->sz-1, DPL_USER);
+  c->gdt[SEG_UDATA] = SEG(STA_W, (uint)cp->mem, cp->sz-1, DPL_USER);
+  c->gdt[SEG_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
+  c->gdt[SEG_TSS].s = 0;
+  c->ts.ss0 = SEG_KDATA << 3;
+  c->ts.esp0 = (uint)cp->kstack + KSTACKSIZE;
+  ltr(SEG_TSS << 3);
+  popcli();
+}
+//PAGEBREAK: 15
 // Look in the process table for an UNUSED proc.
 // If found, change state to EMBRYO and return it.
 // Otherwise return 0.
@@ -67,6 +140,37 @@ found:
  return p;
 }
+// Set up first user process.
+void
+userinit(void)
+{
+  struct proc *p;
+  extern char _binary_initcode_start[], _binary_initcode_size[];
+  p = allocproc();
+  initproc = p;
+  // Initialize memory from initcode.S
+  p->sz = PAGE;
+  p->mem = kalloc(p->sz);
+  memset(p->mem, 0, p->sz);
+  memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
+  memset(p->tf, 0, sizeof(*p->tf));
+  p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
+  p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
+  p->tf->es = p->tf->ds;
+  p->tf->ss = p->tf->ds;
+  p->tf->eflags = FL_IF;
+  p->tf->esp = p->sz;
+  p->tf->eip = 0;  // beginning of initcode.S
+  safestrcpy(p->name, "initcode", sizeof(p->name));
+  p->cwd = namei("/");
+  p->state = RUNNABLE;
+}
 // Grow current process's memory by n bytes.
 // Return 0 on success, -1 on failure.
 int
@@ -86,41 +190,6 @@ growproc(int n)
  return 0;
 }
-// Set up CPU's kernel segment descriptors.
-// Run once at boot time on each CPU.
-void
-ksegment(void)
-{
-  struct cpu *c1;
-  c1 = &cpus[cpu()];
-  c1->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
-  c1->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
-  c1->gdt[SEG_KCPU] = SEG(STA_W, (uint)(&c1->tls+1), 0xffffffff, 0);
-  lgdt(c1->gdt, sizeof(c1->gdt));
-  loadfsgs(SEG_KCPU << 3);
-  // Initialize cpu-local variables.
-  c = c1;
-  cp = 0;
-}
-// Set up CPU's segment descriptors and task state for the current process.
-// If cp==0, set up for "idle" state for when scheduler() is running.
-void
-usegment(void)
-{
-  pushcli();
-  c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)cp->mem, cp->sz-1, DPL_USER);
-  c->gdt[SEG_UDATA] = SEG(STA_W, (uint)cp->mem, cp->sz-1, DPL_USER);
-  c->gdt[SEG_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
-  c->gdt[SEG_TSS].s = 0;
-  c->ts.ss0 = SEG_KDATA << 3;
-  c->ts.esp0 = (uint)cp->kstack + KSTACKSIZE;
-  ltr(SEG_TSS << 3);
-  popcli();
-}
 // Create a new process copying p as the parent.
 // Sets up stack to return as if from system call.
 // Caller must set state of returned proc to RUNNABLE.
@@ -160,37 +229,6 @@ fork(void)
  return pid;
 }
-// Set up first user process.
-void
-userinit(void)
-{
-  struct proc *p;
-  extern char _binary_initcode_start[], _binary_initcode_size[];
-  p = allocproc();
-  initproc = p;
-  // Initialize memory from initcode.S
-  p->sz = PAGE;
-  p->mem = kalloc(p->sz);
-  memset(p->mem, 0, p->sz);
-  memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
-  memset(p->tf, 0, sizeof(*p->tf));
-  p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
-  p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
-  p->tf->es = p->tf->ds;
-  p->tf->ss = p->tf->ds;
-  p->tf->eflags = FL_IF;
-  p->tf->esp = p->sz;
-  p->tf->eip = 0;  // beginning of initcode.S
-  safestrcpy(p->name, "initcode", sizeof(p->name));
-  p->cwd = namei("/");
-  p->state = RUNNABLE;
-}
 //PAGEBREAK: 42
 // Per-CPU process scheduler.
 // Each CPU calls scheduler() after setting itself up.
@@ -440,39 +478,3 @@ wait(void)
  }
 }
-// Print a process listing to console.  For debugging.
-// Runs when user types ^P on console.
-// No lock to avoid wedging a stuck machine further.
-void
-procdump(void)
-{
-  static char *states[] = {
-  [UNUSED]    "unused",
-  [EMBRYO]    "embryo",
-  [SLEEPING]  "sleep ",
-  [RUNNABLE]  "runble",
-  [RUNNING]   "run   ",
-  [ZOMBIE]    "zombie"
-  };
-  int i;
-  struct proc *p;
-  char *state;
-  uint pc[10];
-  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
-    if(p->state == UNUSED)
-      continue;
-    if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
-      state = states[p->state];
-    else
-      state = "???";
-    cprintf("%d %s %s", p->pid, state, p->name);
-    if(p->state == SLEEPING){
-      getcallerpcs((uint*)p->context->ebp+2, pc);
-      for(i=0; i<10 && pc[i] != 0; i++)
-        cprintf(" %p", pc[i]);
-    }
-    cprintf("\n");
-  }
-}
--- a/runoff
+++ b/runoff
@@ -45,6 +45,7 @@ cat toc.ftr >>fmt/toc
 # check for bad alignments
 perl -e '
+	$leftwarn = 0;
 	while(<>){
 		chomp;
 		s!#.*!!;
@@ -75,12 +76,35 @@ perl -e '
 				print STDERR "Have no toc for $file\n";
 				next;
 			}
-			if($toc{$file} =~ /^\d\d[^5]/){
+			if($toc{$file} !~ /^\d\d5/){
 				print STDERR "$file does not start on a second half page.\n";
 			}
 			next;
 		}
+		if(/(left|right): (.*)/){
+			$what = $1;
+			$file = $2;
+			if(!defined($toc{$file})){
+				print STDERR "Have no toc for $file\n";
+				next;
+			}
+			# this assumes that sheet 1 of code is a left page
+			# double-check the PDF
+			if(!$leftwarn++) {
+				print STDERR "assuming that sheet 1 is a left page.  double-check!\n";
+			}
+			if($what eq "left" && !($toc{$file} =~ /^\d[13579]0/)){
+				print STDERR "$file does not start on a fresh left page [$toc{$file}]\n";
+			}
+			# why does this not work if I inline $x in the if?
+			$x = ($toc{$file} =~ /^\d[02468]0/);
+			if($what eq "right" && !$x){
+				print STDERR "$file does not start on a fresh right page [$toc{$file}] [$x]\n";
+			}
+			next;
+		}
 		print STDERR "Unknown spec: $_\n";
 	}
 ' fmt/tocdata runoff.spec

--- a/runoff.list
+++ b/runoff.list
@@ -34,12 +34,10 @@ sysproc.c
 # file system
 buf.h
-dev.h
 fcntl.h
 stat.h
-file.h
 fs.h
-fsvar.h
+file.h
 ide.c
 bio.c
 fs.c

--- a/runoff.spec
+++ b/runoff.spec
@@ -12,20 +12,27 @@ even: bootother.S  # mild preference
 # bootmain.c either
 even: main.c
 # mp.c don't care at all
-even: initcode.S
+# even: initcode.S
-odd: init.c
+# odd: init.c
 # spinlock.h either
 # spinlock.c either
 even: proc.h  # mild preference
-even: proc.c  # VERY important
+# goal is to have two action-packed 2-page spreads,
+# one with
+#     ksegment usegment allocproc userinit growproc fork
+# and another with
+#     scheduler sched yield forkret sleep wakeup1 wakeup
+right: proc.c   # VERY important
 # setjmp.S either
 # kalloc.c either
 # syscall.h either
 # trapasm.S either
 # traps.h either
-even: trap.c  # important
+# even: trap.c
 # vectors.pl either
 # syscall.c either
 # sysproc.c either
@@ -37,7 +44,7 @@ even: trap.c  # important
 # file.h either
 # fs.h either
 # fsvar.h either
-# even: ide.c
+left: ide.c
 # odd: bio.c
 odd: fs.c   # VERY important
 # file.c either
@@ -46,5 +53,6 @@ odd: fs.c   # VERY important
 # even: pipe.c  # mild preference
 # string.c either
+left: kbd.h
 even: console.c
 odd: sh.c
--- a/sysfile.c
+++ b/sysfile.c
@@ -5,7 +5,6 @@
 #include "mmu.h"
 #include "proc.h"
 #include "fs.h"
-#include "fsvar.h"
 #include "file.h"
 #include "fcntl.h"

--- a/timer.c
+++ b/timer.c
@@ -30,36 +30,3 @@ timerinit(void)
  outb(IO_TIMER1, TIMER_DIV(100) / 256);
  picenable(IRQ_TIMER);
 }
-// Blank page
--- a/trap.c
+++ b/trap.c
@@ -31,6 +31,7 @@ idtinit(void)
  lidt(idt, sizeof(idt));
 }
+//PAGEBREAK: 41
 void
 trap(struct trapframe *tf)
 {

--- a/uart.c
+++ b/uart.c
@@ -5,7 +5,8 @@
 #include "param.h"
 #include "traps.h"
 #include "spinlock.h"
-#include "dev.h"
+#include "fs.h"
+#include "file.h"
 #include "mmu.h"
 #include "proc.h"
 #include "x86.h"

--- a/x86.h
+++ b/x86.h
@@ -122,6 +122,7 @@ sti(void)
  asm volatile("sti");
 }
+//PAGEBREAK: 36
 // Layout of the trap frame built on the stack by the
 // hardware and by trapasm.S, and passed to trap().
 struct trapframe {

--- a/xv6.pdf
+++ b/xv6.pdf
--- a/xv6.ps
+++ b/xv6.ps