diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index 8a99d790638..7542ae78010 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -68,7 +68,6 @@ DIRS=\
 	debug/elf\
 	debug/gosym\
 	debug/pe\
-	debug/proc\
 	ebnf\
 	encoding/ascii85\
 	encoding/base32\
@@ -187,7 +186,6 @@ endif
 ifeq ($(GOOS),plan9)
 NOPLAN9BUILD=\
 	crypto/tls\
-	debug/proc\
 	exp/gui/x11\
 	expvar\
 	http\
@@ -218,7 +216,6 @@ NOTEST+=\
 	crypto\
 	crypto/openpgp/error\
 	crypto/x509/pkix\
-	debug/proc\
 	exp/gui\
 	exp/gui/x11\
 	go/ast\
diff --git a/src/pkg/debug/proc/Makefile b/src/pkg/debug/proc/Makefile
deleted file mode 100644
index c6d879836b2..00000000000
--- a/src/pkg/debug/proc/Makefile
+++ /dev/null
@@ -1,13 +0,0 @@
-# Copyright 2009 The Go Authors.  All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
-
-include ../../../Make.inc
-
-TARG=debug/proc
-GOFILES=\
-	proc.go\
-	proc_$(GOOS).go\
-	regs_$(GOOS)_$(GOARCH).go\
-
-include ../../../Make.pkg
diff --git a/src/pkg/debug/proc/proc.go b/src/pkg/debug/proc/proc.go
deleted file mode 100644
index d89649cf887..00000000000
--- a/src/pkg/debug/proc/proc.go
+++ /dev/null
@@ -1,222 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package proc provides a platform-independent interface for
-// tracing and controlling running processes.  It supports
-// multi-threaded processes and provides typical low-level debugging
-// controls such as breakpoints, single stepping, and manipulating
-// memory and registers.
-package proc
-
-// TODO(rsc): Have to import everything that proc_linux.go
-// and proc_darwin.go do, because deps.bash only looks at
-// this file.
-import (
-	_ "container/vector"
-	_ "fmt"
-	_ "io"
-	"os"
-	_ "runtime"
-	"strconv"
-	_ "strings"
-	_ "sync"
-	_ "syscall"
-)
-
-type Word uint64
-
-// A Cause explains why a thread is stopped.
-type Cause interface {
-	String() string
-}
-
-// Regs is a set of named machine registers, including a program
-// counter, link register, and stack pointer.
-//
-// TODO(austin) There's quite a proliferation of methods here.  We
-// could make a Reg interface with Get and Set and make this just PC,
-// Link, SP, Names, and Reg.  We could also put Index in Reg and that
-// makes it easy to get the index of things like the PC (currently
-// there's just no way to know that).  This would also let us include
-// other per-register information like how to print it.
-type Regs interface {
-	// PC returns the value of the program counter.
-	PC() Word
-
-	// SetPC sets the program counter to val.
-	SetPC(val Word) os.Error
-
-	// Link returns the link register, if any.
-	Link() Word
-
-	// SetLink sets the link register to val.
-	SetLink(val Word) os.Error
-
-	// SP returns the value of the stack pointer.
-	SP() Word
-
-	// SetSP sets the stack pointer register to val.
-	SetSP(val Word) os.Error
-
-	// Names returns the names of all of the registers.
-	Names() []string
-
-	// Get returns the value of a register, where i corresponds to
-	// the index of the register's name in the array returned by
-	// Names.
-	Get(i int) Word
-
-	// Set sets the value of a register.
-	Set(i int, val Word) os.Error
-}
-
-// Thread is a thread in the process being traced.
-type Thread interface {
-	// Step steps this thread by a single instruction.  The thread
-	// must be stopped.  If the thread is currently stopped on a
-	// breakpoint, this will step over the breakpoint.
-	//
-	// XXX What if it's stopped because of a signal?
-	Step() os.Error
-
-	// Stopped returns the reason that this thread is stopped.  It
-	// is an error is the thread not stopped.
-	Stopped() (Cause, os.Error)
-
-	// Regs retrieves the current register values from this
-	// thread.  The thread must be stopped.
-	Regs() (Regs, os.Error)
-
-	// Peek reads len(out) bytes from the address addr in this
-	// thread into out.  The thread must be stopped.  It returns
-	// the number of bytes successfully read.  If an error occurs,
-	// such as attempting to read unmapped memory, this count
-	// could be short and an error will be returned.  If this does
-	// encounter unmapped memory, it will read up to the byte
-	// preceding the unmapped area.
-	Peek(addr Word, out []byte) (int, os.Error)
-
-	// Poke writes b to the address addr in this thread.  The
-	// thread must be stopped.  It returns the number of bytes
-	// successfully written.  If an error occurs, such as
-	// attempting to write to unmapped memory, this count could be
-	// short and an error will be returned.  If this does
-	// encounter unmapped memory, it will write up to the byte
-	// preceding the unmapped area.
-	Poke(addr Word, b []byte) (int, os.Error)
-}
-
-// Process is a process being traced.  It consists of a set of
-// threads.  A process can be running, stopped, or terminated.  The
-// process's state extends to all of its threads.
-type Process interface {
-	// Threads returns an array of all threads in this process.
-	Threads() []Thread
-
-	// AddBreakpoint creates a new breakpoint at program counter
-	// pc.  Breakpoints can only be created when the process is
-	// stopped.  It is an error if a breakpoint already exists at
-	// pc.
-	AddBreakpoint(pc Word) os.Error
-
-	// RemoveBreakpoint removes the breakpoint at the program
-	// counter pc.  It is an error if no breakpoint exists at pc.
-	RemoveBreakpoint(pc Word) os.Error
-
-	// Stop stops all running threads in this process before
-	// returning.
-	Stop() os.Error
-
-	// Continue resumes execution of all threads in this process.
-	// Any thread that is stopped on a breakpoint will be stepped
-	// over that breakpoint.  Any thread that is stopped because
-	// of a signal (other than SIGSTOP or SIGTRAP) will receive
-	// the pending signal.
-	Continue() os.Error
-
-	// WaitStop waits until all threads in process p are stopped
-	// as a result of some thread hitting a breakpoint, receiving
-	// a signal, creating a new thread, or exiting.
-	WaitStop() os.Error
-
-	// Detach detaches from this process.  All stopped threads
-	// will be resumed.
-	Detach() os.Error
-}
-
-// Stopped is a stop cause used for threads that are stopped either by
-// user request (e.g., from the Stop method or after single stepping),
-// or that are stopped because some other thread caused the program to
-// stop.
-type Stopped struct{}
-
-func (c Stopped) String() string { return "stopped" }
-
-// Breakpoint is a stop cause resulting from a thread reaching a set
-// breakpoint.
-type Breakpoint Word
-
-// PC returns the program counter that the program is stopped at.
-func (c Breakpoint) PC() Word { return Word(c) }
-
-func (c Breakpoint) String() string {
-	return "breakpoint at 0x" + strconv.Uitob64(uint64(c.PC()), 16)
-}
-
-// Signal is a stop cause resulting from a thread receiving a signal.
-// When the process is continued, the signal will be delivered.
-type Signal string
-
-// Signal returns the signal being delivered to the thread.
-func (c Signal) Name() string { return string(c) }
-
-func (c Signal) String() string { return c.Name() }
-
-// ThreadCreate is a stop cause returned from an existing thread when
-// it creates a new thread.  The new thread exists in a primordial
-// form at this point and will begin executing in earnest when the
-// process is continued.
-type ThreadCreate struct {
-	thread Thread
-}
-
-func (c *ThreadCreate) NewThread() Thread { return c.thread }
-
-func (c *ThreadCreate) String() string { return "thread create" }
-
-// ThreadExit is a stop cause resulting from a thread exiting.  When
-// this cause first arises, the thread will still be in the list of
-// process threads and its registers and memory will still be
-// accessible.
-type ThreadExit struct {
-	exitStatus int
-	signal     string
-}
-
-// Exited returns true if the thread exited normally.
-func (c *ThreadExit) Exited() bool { return c.exitStatus != -1 }
-
-// ExitStatus returns the exit status of the thread if it exited
-// normally or -1 otherwise.
-func (c *ThreadExit) ExitStatus() int { return c.exitStatus }
-
-// Signaled returns true if the thread was terminated by a signal.
-func (c *ThreadExit) Signaled() bool { return c.exitStatus == -1 }
-
-// StopSignal returns the signal that terminated the thread, or "" if
-// it was not terminated by a signal.
-func (c *ThreadExit) StopSignal() string { return c.signal }
-
-func (c *ThreadExit) String() string {
-	res := "thread exited "
-	switch {
-	case c.Exited():
-		res += "with status " + strconv.Itoa(c.ExitStatus())
-	case c.Signaled():
-		res += "from signal " + c.StopSignal()
-	default:
-		res += "from unknown cause"
-	}
-	return res
-}
diff --git a/src/pkg/debug/proc/proc_darwin.go b/src/pkg/debug/proc/proc_darwin.go
deleted file mode 100644
index 49f0a5361fb..00000000000
--- a/src/pkg/debug/proc/proc_darwin.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import "os"
-
-// Process tracing is not supported on OS X yet.
-
-func Attach(pid int) (Process, os.Error) {
-	return nil, os.NewError("debug/proc not implemented on OS X")
-}
-
-func StartProcess(argv0 string, argv []string, attr *os.ProcAttr) (Process, os.Error) {
-	return Attach(0)
-}
diff --git a/src/pkg/debug/proc/proc_freebsd.go b/src/pkg/debug/proc/proc_freebsd.go
deleted file mode 100644
index 4df07c365af..00000000000
--- a/src/pkg/debug/proc/proc_freebsd.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import "os"
-
-// Process tracing is not supported on FreeBSD yet.
-
-func Attach(pid int) (Process, os.Error) {
-	return nil, os.NewError("debug/proc not implemented on FreeBSD")
-}
-
-func StartProcess(argv0 string, argv []string, attr *os.ProcAttr) (Process, os.Error) {
-	return Attach(0)
-}
diff --git a/src/pkg/debug/proc/proc_linux.go b/src/pkg/debug/proc/proc_linux.go
deleted file mode 100644
index 7ec797114c4..00000000000
--- a/src/pkg/debug/proc/proc_linux.go
+++ /dev/null
@@ -1,1324 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-// TODO(rsc): Imports here after to be in proc.go too in order
-// for deps.bash to get the right answer.
-import (
-	"container/vector"
-	"fmt"
-	"io/ioutil"
-	"os"
-	"runtime"
-	"strconv"
-	"strings"
-	"sync"
-	"syscall"
-)
-
-// This is an implementation of the process tracing interface using
-// Linux's ptrace(2) interface.  The implementation is multi-threaded.
-// Each attached process has an associated monitor thread, and each
-// running attached thread has an associated "wait" thread.  The wait
-// thread calls wait4 on the thread's TID and reports any wait events
-// or errors via "debug events".  The monitor thread consumes these
-// wait events and updates the internally maintained state of each
-// thread.  All ptrace calls must run in the monitor thread, so the
-// monitor executes closures received on the debugReq channel.
-//
-// As ptrace's documentation is somewhat light, this is heavily based
-// on information gleaned from the implementation of ptrace found at
-//   http://lxr.linux.no/linux+v2.6.30/kernel/ptrace.c
-//   http://lxr.linux.no/linux+v2.6.30/arch/x86/kernel/ptrace.c#L854
-// as well as experimentation and examination of gdb's behavior.
-
-const (
-	trace    = false
-	traceIP  = false
-	traceMem = false
-)
-
-/*
- * Thread state
- */
-
-// Each thread can be in one of the following set of states.
-// Each state satisfies
-//  isRunning() || isStopped() || isZombie() || isTerminal().
-//
-// Running threads can be sent signals and must be waited on, but they
-// cannot be inspected using ptrace.
-//
-// Stopped threads can be inspected and continued, but cannot be
-// meaningfully waited on.  They can be sent signals, but the signals
-// will be queued until they are running again.
-//
-// Zombie threads cannot be inspected, continued, or sent signals (and
-// therefore they cannot be stopped), but they must be waited on.
-//
-// Terminal threads no longer exist in the OS and thus you can't do
-// anything with them.
-type threadState string
-
-const (
-	running             threadState = "Running"
-	singleStepping      threadState = "SingleStepping" // Transient
-	stopping            threadState = "Stopping"       // Transient
-	stopped             threadState = "Stopped"
-	stoppedBreakpoint   threadState = "StoppedBreakpoint"
-	stoppedSignal       threadState = "StoppedSignal"
-	stoppedThreadCreate threadState = "StoppedThreadCreate"
-	stoppedExiting      threadState = "StoppedExiting"
-	exiting             threadState = "Exiting" // Transient (except main thread)
-	exited              threadState = "Exited"
-	detached            threadState = "Detached"
-)
-
-func (ts threadState) isRunning() bool {
-	return ts == running || ts == singleStepping || ts == stopping
-}
-
-func (ts threadState) isStopped() bool {
-	return ts == stopped || ts == stoppedBreakpoint || ts == stoppedSignal || ts == stoppedThreadCreate || ts == stoppedExiting
-}
-
-func (ts threadState) isZombie() bool { return ts == exiting }
-
-func (ts threadState) isTerminal() bool { return ts == exited || ts == detached }
-
-func (ts threadState) String() string { return string(ts) }
-
-/*
- * Basic types
- */
-
-// A breakpoint stores information about a single breakpoint,
-// including its program counter, the overwritten text if the
-// breakpoint is installed.
-type breakpoint struct {
-	pc      uintptr
-	olddata []byte
-}
-
-func (bp *breakpoint) String() string {
-	if bp == nil {
-		return "<nil>"
-	}
-	return fmt.Sprintf("%#x", bp.pc)
-}
-
-// bpinst386 is the breakpoint instruction used on 386 and amd64.
-var bpinst386 = []byte{0xcc}
-
-// A debugEvent represents a reason a thread stopped or a wait error.
-type debugEvent struct {
-	*os.Waitmsg
-	t   *thread
-	err os.Error
-}
-
-// A debugReq is a request to execute a closure in the monitor thread.
-type debugReq struct {
-	f   func() os.Error
-	res chan os.Error
-}
-
-// A transitionHandler specifies a function to be called when a thread
-// changes state and a function to be called when an error occurs in
-// the monitor.  Both run in the monitor thread.  Before the monitor
-// invokes a handler, it removes the handler from the handler queue.
-// The handler should re-add itself if needed.
-type transitionHandler struct {
-	handle func(*thread, threadState, threadState)
-	onErr  func(os.Error)
-}
-
-// A process is a Linux process, which consists of a set of threads.
-// Each running process has one monitor thread, which processes
-// messages from the debugEvents, debugReqs, and stopReq channels and
-// calls transition handlers.
-//
-// To send a message to the monitor thread, first receive from the
-// ready channel.  If the ready channel returns true, the monitor is
-// still running and will accept a message.  If the ready channel
-// returns false, the monitor is not running (the ready channel has
-// been closed), and the reason it is not running will be stored in err.
-type process struct {
-	pid                int
-	threads            map[int]*thread
-	breakpoints        map[uintptr]*breakpoint
-	ready              chan bool
-	debugEvents        chan *debugEvent
-	debugReqs          chan *debugReq
-	stopReq            chan os.Error
-	transitionHandlers vector.Vector
-	err                os.Error
-}
-
-// A thread represents a Linux thread in another process that is being
-// debugged.  Each running thread has an associated goroutine that
-// waits for thread updates and sends them to the process monitor.
-type thread struct {
-	tid  int
-	proc *process
-	// Whether to ignore the next SIGSTOP received by wait.
-	ignoreNextSigstop bool
-
-	// Thread state.  Only modified via setState.
-	state threadState
-	// If state == StoppedBreakpoint
-	breakpoint *breakpoint
-	// If state == StoppedSignal or state == Exited
-	signal int
-	// If state == StoppedThreadCreate
-	newThread *thread
-	// If state == Exited
-	exitStatus int
-}
-
-/*
- * Errors
- */
-
-type badState struct {
-	thread  *thread
-	message string
-	state   threadState
-}
-
-func (e *badState) String() string {
-	return fmt.Sprintf("Thread %d %s from state %v", e.thread.tid, e.message, e.state)
-}
-
-type breakpointExistsError Word
-
-func (e breakpointExistsError) String() string {
-	return fmt.Sprintf("breakpoint already exists at PC %#x", e)
-}
-
-type noBreakpointError Word
-
-func (e noBreakpointError) String() string { return fmt.Sprintf("no breakpoint at PC %#x", e) }
-
-type newThreadError struct {
-	*os.Waitmsg
-	wantPid int
-	wantSig int
-}
-
-func (e *newThreadError) String() string {
-	return fmt.Sprintf("newThread wait wanted pid %v and signal %v, got %v and %v", e.Pid, e.StopSignal(), e.wantPid, e.wantSig)
-}
-
-type ProcessExited struct{}
-
-func (p ProcessExited) String() string { return "process exited" }
-
-/*
- * Ptrace wrappers
- */
-
-func (t *thread) ptracePeekText(addr uintptr, out []byte) (int, os.Error) {
-	c, err := syscall.PtracePeekText(t.tid, addr, out)
-	if traceMem {
-		fmt.Printf("peek(%#x) => %v, %v\n", addr, out, err)
-	}
-	return c, os.NewSyscallError("ptrace(PEEKTEXT)", err)
-}
-
-func (t *thread) ptracePokeText(addr uintptr, out []byte) (int, os.Error) {
-	c, err := syscall.PtracePokeText(t.tid, addr, out)
-	if traceMem {
-		fmt.Printf("poke(%#x, %v) => %v\n", addr, out, err)
-	}
-	return c, os.NewSyscallError("ptrace(POKETEXT)", err)
-}
-
-func (t *thread) ptraceGetRegs(regs *syscall.PtraceRegs) os.Error {
-	err := syscall.PtraceGetRegs(t.tid, regs)
-	return os.NewSyscallError("ptrace(GETREGS)", err)
-}
-
-func (t *thread) ptraceSetRegs(regs *syscall.PtraceRegs) os.Error {
-	err := syscall.PtraceSetRegs(t.tid, regs)
-	return os.NewSyscallError("ptrace(SETREGS)", err)
-}
-
-func (t *thread) ptraceSetOptions(options int) os.Error {
-	err := syscall.PtraceSetOptions(t.tid, options)
-	return os.NewSyscallError("ptrace(SETOPTIONS)", err)
-}
-
-func (t *thread) ptraceGetEventMsg() (uint, os.Error) {
-	msg, err := syscall.PtraceGetEventMsg(t.tid)
-	return msg, os.NewSyscallError("ptrace(GETEVENTMSG)", err)
-}
-
-func (t *thread) ptraceCont() os.Error {
-	err := syscall.PtraceCont(t.tid, 0)
-	return os.NewSyscallError("ptrace(CONT)", err)
-}
-
-func (t *thread) ptraceContWithSignal(sig int) os.Error {
-	err := syscall.PtraceCont(t.tid, sig)
-	return os.NewSyscallError("ptrace(CONT)", err)
-}
-
-func (t *thread) ptraceStep() os.Error {
-	err := syscall.PtraceSingleStep(t.tid)
-	return os.NewSyscallError("ptrace(SINGLESTEP)", err)
-}
-
-func (t *thread) ptraceDetach() os.Error {
-	err := syscall.PtraceDetach(t.tid)
-	return os.NewSyscallError("ptrace(DETACH)", err)
-}
-
-/*
- * Logging utilities
- */
-
-var logLock sync.Mutex
-
-func (t *thread) logTrace(format string, args ...interface{}) {
-	if !trace {
-		return
-	}
-	logLock.Lock()
-	defer logLock.Unlock()
-	fmt.Fprintf(os.Stderr, "Thread %d", t.tid)
-	if traceIP {
-		var regs syscall.PtraceRegs
-		err := t.ptraceGetRegs(&regs)
-		if err == nil {
-			fmt.Fprintf(os.Stderr, "@%x", regs.PC())
-		}
-	}
-	fmt.Fprint(os.Stderr, ": ")
-	fmt.Fprintf(os.Stderr, format, args...)
-	fmt.Fprint(os.Stderr, "\n")
-}
-
-func (t *thread) warn(format string, args ...interface{}) {
-	logLock.Lock()
-	defer logLock.Unlock()
-	fmt.Fprintf(os.Stderr, "Thread %d: WARNING ", t.tid)
-	fmt.Fprintf(os.Stderr, format, args...)
-	fmt.Fprint(os.Stderr, "\n")
-}
-
-func (p *process) logTrace(format string, args ...interface{}) {
-	if !trace {
-		return
-	}
-	logLock.Lock()
-	defer logLock.Unlock()
-	fmt.Fprintf(os.Stderr, "Process %d: ", p.pid)
-	fmt.Fprintf(os.Stderr, format, args...)
-	fmt.Fprint(os.Stderr, "\n")
-}
-
-/*
- * State utilities
- */
-
-// someStoppedThread returns a stopped thread from the process.
-// Returns nil if no threads are stopped.
-//
-// Must be called from the monitor thread.
-func (p *process) someStoppedThread() *thread {
-	for _, t := range p.threads {
-		if t.state.isStopped() {
-			return t
-		}
-	}
-	return nil
-}
-
-// someRunningThread returns a running thread from the process.
-// Returns nil if no threads are running.
-//
-// Must be called from the monitor thread.
-func (p *process) someRunningThread() *thread {
-	for _, t := range p.threads {
-		if t.state.isRunning() {
-			return t
-		}
-	}
-	return nil
-}
-
-/*
- * Breakpoint utilities
- */
-
-// installBreakpoints adds breakpoints to the attached process.
-//
-// Must be called from the monitor thread.
-func (p *process) installBreakpoints() os.Error {
-	n := 0
-	main := p.someStoppedThread()
-	for _, b := range p.breakpoints {
-		if b.olddata != nil {
-			continue
-		}
-
-		b.olddata = make([]byte, len(bpinst386))
-		_, err := main.ptracePeekText(uintptr(b.pc), b.olddata)
-		if err != nil {
-			b.olddata = nil
-			return err
-		}
-
-		_, err = main.ptracePokeText(uintptr(b.pc), bpinst386)
-		if err != nil {
-			b.olddata = nil
-			return err
-		}
-		n++
-	}
-	if n > 0 {
-		p.logTrace("installed %d/%d breakpoints", n, len(p.breakpoints))
-	}
-
-	return nil
-}
-
-// uninstallBreakpoints removes the installed breakpoints from p.
-//
-// Must be called from the monitor thread.
-func (p *process) uninstallBreakpoints() os.Error {
-	if len(p.threads) == 0 {
-		return nil
-	}
-	n := 0
-	main := p.someStoppedThread()
-	for _, b := range p.breakpoints {
-		if b.olddata == nil {
-			continue
-		}
-
-		_, err := main.ptracePokeText(uintptr(b.pc), b.olddata)
-		if err != nil {
-			return err
-		}
-		b.olddata = nil
-		n++
-	}
-	if n > 0 {
-		p.logTrace("uninstalled %d/%d breakpoints", n, len(p.breakpoints))
-	}
-
-	return nil
-}
-
-/*
- * Debug event handling
- */
-
-// wait waits for a wait event from this thread and sends it on the
-// debug events channel for this thread's process.  This should be
-// started in its own goroutine when the attached thread enters a
-// running state.  The goroutine will exit as soon as it sends a debug
-// event.
-func (t *thread) wait() {
-	for {
-		var ev debugEvent
-		ev.t = t
-		t.logTrace("beginning wait")
-		ev.Waitmsg, ev.err = os.Wait(t.tid, syscall.WALL)
-		if ev.err == nil && ev.Pid != t.tid {
-			panic(fmt.Sprint("Wait returned pid ", ev.Pid, " wanted ", t.tid))
-		}
-		if ev.StopSignal() == syscall.SIGSTOP && t.ignoreNextSigstop {
-			// Spurious SIGSTOP.  See Thread.Stop().
-			t.ignoreNextSigstop = false
-			err := t.ptraceCont()
-			if err == nil {
-				continue
-			}
-			// If we failed to continue, just let
-			// the stop go through so we can
-			// update the thread's state.
-		}
-		if !<-t.proc.ready {
-			// The monitor exited
-			break
-		}
-		t.proc.debugEvents <- &ev
-		break
-	}
-}
-
-// setState sets this thread's state, starts a wait thread if
-// necessary, and invokes state transition handlers.
-//
-// Must be called from the monitor thread.
-func (t *thread) setState(newState threadState) {
-	oldState := t.state
-	t.state = newState
-	t.logTrace("state %v -> %v", oldState, newState)
-
-	if !oldState.isRunning() && (newState.isRunning() || newState.isZombie()) {
-		// Start waiting on this thread
-		go t.wait()
-	}
-
-	// Invoke state change handlers
-	handlers := t.proc.transitionHandlers
-	if handlers.Len() == 0 {
-		return
-	}
-
-	t.proc.transitionHandlers = nil
-	for _, h := range handlers {
-		h := h.(*transitionHandler)
-		h.handle(t, oldState, newState)
-	}
-}
-
-// sendSigstop sends a SIGSTOP to this thread.
-func (t *thread) sendSigstop() os.Error {
-	t.logTrace("sending SIGSTOP")
-	err := syscall.Tgkill(t.proc.pid, t.tid, syscall.SIGSTOP)
-	return os.NewSyscallError("tgkill", err)
-}
-
-// stopAsync sends SIGSTOP to all threads in state 'running'.
-//
-// Must be called from the monitor thread.
-func (p *process) stopAsync() os.Error {
-	for _, t := range p.threads {
-		if t.state == running {
-			err := t.sendSigstop()
-			if err != nil {
-				return err
-			}
-			t.setState(stopping)
-		}
-	}
-	return nil
-}
-
-// doTrap handles SIGTRAP debug events with a cause of 0.  These can
-// be caused either by an installed breakpoint, a breakpoint in the
-// program text, or by single stepping.
-//
-// TODO(austin) I think we also get this on an execve syscall.
-func (ev *debugEvent) doTrap() (threadState, os.Error) {
-	t := ev.t
-
-	if t.state == singleStepping {
-		return stopped, nil
-	}
-
-	// Hit a breakpoint.  Linux leaves the program counter after
-	// the breakpoint.  If this is an installed breakpoint, we
-	// need to back the PC up to the breakpoint PC.
-	var regs syscall.PtraceRegs
-	err := t.ptraceGetRegs(&regs)
-	if err != nil {
-		return stopped, err
-	}
-
-	b, ok := t.proc.breakpoints[uintptr(regs.PC())-uintptr(len(bpinst386))]
-	if !ok {
-		// We must have hit a breakpoint that was actually in
-		// the program.  Leave the IP where it is so we don't
-		// re-execute the breakpoint instruction.  Expose the
-		// fact that we stopped with a SIGTRAP.
-		return stoppedSignal, nil
-	}
-
-	t.breakpoint = b
-	t.logTrace("at breakpoint %v, backing up PC from %#x", b, regs.PC())
-
-	regs.SetPC(uint64(b.pc))
-	err = t.ptraceSetRegs(&regs)
-	if err != nil {
-		return stopped, err
-	}
-	return stoppedBreakpoint, nil
-}
-
-// doPtraceClone handles SIGTRAP debug events with a PTRACE_EVENT_CLONE
-// cause.  It initializes the new thread, adds it to the process, and
-// returns the appropriate thread state for the existing thread.
-func (ev *debugEvent) doPtraceClone() (threadState, os.Error) {
-	t := ev.t
-
-	// Get the TID of the new thread
-	tid, err := t.ptraceGetEventMsg()
-	if err != nil {
-		return stopped, err
-	}
-
-	nt, err := t.proc.newThread(int(tid), syscall.SIGSTOP, true)
-	if err != nil {
-		return stopped, err
-	}
-
-	// Remember the thread
-	t.newThread = nt
-
-	return stoppedThreadCreate, nil
-}
-
-// doPtraceExit handles SIGTRAP debug events with a PTRACE_EVENT_EXIT
-// cause.  It sets up the thread's state, but does not remove it from
-// the process.  A later WIFEXITED debug event will remove it from the
-// process.
-func (ev *debugEvent) doPtraceExit() (threadState, os.Error) {
-	t := ev.t
-
-	// Get exit status
-	exitStatus, err := t.ptraceGetEventMsg()
-	if err != nil {
-		return stopped, err
-	}
-	ws := syscall.WaitStatus(exitStatus)
-	t.logTrace("exited with %v", ws)
-	switch {
-	case ws.Exited():
-		t.exitStatus = ws.ExitStatus()
-	case ws.Signaled():
-		t.signal = ws.Signal()
-	}
-
-	// We still need to continue this thread and wait on this
-	// thread's WIFEXITED event.  We'll delete it then.
-	return stoppedExiting, nil
-}
-
-// process handles a debug event.  It modifies any thread or process
-// state as necessary, uninstalls breakpoints if necessary, and stops
-// any running threads.
-func (ev *debugEvent) process() os.Error {
-	if ev.err != nil {
-		return ev.err
-	}
-
-	t := ev.t
-	t.exitStatus = -1
-	t.signal = -1
-
-	// Decode wait status.
-	var state threadState
-	switch {
-	case ev.Stopped():
-		state = stoppedSignal
-		t.signal = ev.StopSignal()
-		t.logTrace("stopped with %v", ev)
-		if ev.StopSignal() == syscall.SIGTRAP {
-			// What caused the debug trap?
-			var err os.Error
-			switch cause := ev.TrapCause(); cause {
-			case 0:
-				// Breakpoint or single stepping
-				state, err = ev.doTrap()
-
-			case syscall.PTRACE_EVENT_CLONE:
-				state, err = ev.doPtraceClone()
-
-			case syscall.PTRACE_EVENT_EXIT:
-				state, err = ev.doPtraceExit()
-
-			default:
-				t.warn("Unknown trap cause %d", cause)
-			}
-
-			if err != nil {
-				t.setState(stopped)
-				t.warn("failed to handle trap %v: %v", ev, err)
-			}
-		}
-
-	case ev.Exited():
-		state = exited
-		t.proc.threads[t.tid] = nil, false
-		t.logTrace("exited %v", ev)
-		// We should have gotten the exit status in
-		// PTRACE_EVENT_EXIT, but just in case.
-		t.exitStatus = ev.ExitStatus()
-
-	case ev.Signaled():
-		state = exited
-		t.proc.threads[t.tid] = nil, false
-		t.logTrace("signaled %v", ev)
-		// Again, this should be redundant.
-		t.signal = ev.Signal()
-
-	default:
-		panic(fmt.Sprintf("Unexpected wait status %v", ev.Waitmsg))
-	}
-
-	// If we sent a SIGSTOP to the thread (indicated by state
-	// Stopping), we might have raced with a different type of
-	// stop.  If we didn't get the stop we expected, then the
-	// SIGSTOP we sent is now queued up, so we should ignore the
-	// next one we get.
-	if t.state == stopping && ev.StopSignal() != syscall.SIGSTOP {
-		t.ignoreNextSigstop = true
-	}
-
-	// TODO(austin) If we're in state stopping and get a SIGSTOP,
-	// set state stopped instead of stoppedSignal.
-
-	t.setState(state)
-
-	if t.proc.someRunningThread() == nil {
-		// Nothing is running, uninstall breakpoints
-		return t.proc.uninstallBreakpoints()
-	}
-	// Stop any other running threads
-	return t.proc.stopAsync()
-}
-
-// onStop adds a handler for state transitions from running to
-// non-running states.  The handler will be called from the monitor
-// thread.
-//
-// Must be called from the monitor thread.
-func (t *thread) onStop(handle func(), onErr func(os.Error)) {
-	// TODO(austin) This is rather inefficient for things like
-	// stepping all threads during a continue.  Maybe move
-	// transitionHandlers to the thread, or have both per-thread
-	// and per-process transition handlers.
-	h := &transitionHandler{nil, onErr}
-	h.handle = func(st *thread, old, new threadState) {
-		if t == st && old.isRunning() && !new.isRunning() {
-			handle()
-		} else {
-			t.proc.transitionHandlers.Push(h)
-		}
-	}
-	t.proc.transitionHandlers.Push(h)
-}
-
-/*
- * Event monitor
- */
-
-// monitor handles debug events and debug requests for p, exiting when
-// there are no threads left in p.
-func (p *process) monitor() {
-	var err os.Error
-
-	// Linux requires that all ptrace calls come from the thread
-	// that originally attached.  Prevent the Go scheduler from
-	// migrating us to other OS threads.
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
-	hadThreads := false
-	for err == nil {
-		p.ready <- true
-		select {
-		case event := <-p.debugEvents:
-			err = event.process()
-
-		case req := <-p.debugReqs:
-			req.res <- req.f()
-
-		case err = <-p.stopReq:
-			break
-		}
-
-		if len(p.threads) == 0 {
-			if err == nil && hadThreads {
-				p.logTrace("no more threads; monitor exiting")
-				err = ProcessExited{}
-			}
-		} else {
-			hadThreads = true
-		}
-	}
-
-	// Abort waiting handlers
-	// TODO(austin) How do I stop the wait threads?
-	for _, h := range p.transitionHandlers {
-		h := h.(*transitionHandler)
-		h.onErr(err)
-	}
-
-	// Indicate that the monitor cannot receive any more messages
-	p.err = err
-	close(p.ready)
-}
-
-// do executes f in the monitor thread (and, thus, atomically with
-// respect to thread state changes).  f must not block.
-//
-// Must NOT be called from the monitor thread.
-func (p *process) do(f func() os.Error) os.Error {
-	if !<-p.ready {
-		return p.err
-	}
-	req := &debugReq{f, make(chan os.Error)}
-	p.debugReqs <- req
-	return <-req.res
-}
-
-// stopMonitor stops the monitor with the given error.  If the monitor
-// is already stopped, does nothing.
-func (p *process) stopMonitor(err os.Error) {
-	if err == nil {
-		panic("cannot stop the monitor with no error")
-	}
-	if <-p.ready {
-		p.stopReq <- err
-	}
-}
-
-/*
- * Public thread interface
- */
-
-func (t *thread) Regs() (Regs, os.Error) {
-	var regs syscall.PtraceRegs
-
-	err := t.proc.do(func() os.Error {
-		if !t.state.isStopped() {
-			return &badState{t, "cannot get registers", t.state}
-		}
-		return t.ptraceGetRegs(&regs)
-	})
-	if err != nil {
-		return nil, err
-	}
-
-	setter := func(r *syscall.PtraceRegs) os.Error {
-		return t.proc.do(func() os.Error {
-			if !t.state.isStopped() {
-				return &badState{t, "cannot get registers", t.state}
-			}
-			return t.ptraceSetRegs(r)
-		})
-	}
-	return newRegs(&regs, setter), nil
-}
-
-func (t *thread) Peek(addr Word, out []byte) (int, os.Error) {
-	var c int
-
-	err := t.proc.do(func() os.Error {
-		if !t.state.isStopped() {
-			return &badState{t, "cannot peek text", t.state}
-		}
-
-		var err os.Error
-		c, err = t.ptracePeekText(uintptr(addr), out)
-		return err
-	})
-
-	return c, err
-}
-
-func (t *thread) Poke(addr Word, out []byte) (int, os.Error) {
-	var c int
-
-	err := t.proc.do(func() os.Error {
-		if !t.state.isStopped() {
-			return &badState{t, "cannot poke text", t.state}
-		}
-
-		var err os.Error
-		c, err = t.ptracePokeText(uintptr(addr), out)
-		return err
-	})
-
-	return c, err
-}
-
-// stepAsync starts this thread single stepping.  When the single step
-// is complete, it will send nil on the given channel.  If an error
-// occurs while setting up the single step, it returns that error.  If
-// an error occurs while waiting for the single step to complete, it
-// sends that error on the channel.
-func (t *thread) stepAsync(ready chan os.Error) os.Error {
-	if err := t.ptraceStep(); err != nil {
-		return err
-	}
-	t.setState(singleStepping)
-	t.onStop(func() { ready <- nil },
-		func(err os.Error) { ready <- err })
-	return nil
-}
-
-func (t *thread) Step() os.Error {
-	t.logTrace("Step {")
-	defer t.logTrace("}")
-
-	ready := make(chan os.Error)
-
-	err := t.proc.do(func() os.Error {
-		if !t.state.isStopped() {
-			return &badState{t, "cannot single step", t.state}
-		}
-		return t.stepAsync(ready)
-	})
-	if err != nil {
-		return err
-	}
-
-	err = <-ready
-	return err
-}
-
-// TODO(austin) We should probably get this via C's strsignal.
-var sigNames = [...]string{
-	"SIGEXIT", "SIGHUP", "SIGINT", "SIGQUIT", "SIGILL",
-	"SIGTRAP", "SIGABRT", "SIGBUS", "SIGFPE", "SIGKILL",
-	"SIGUSR1", "SIGSEGV", "SIGUSR2", "SIGPIPE", "SIGALRM",
-	"SIGTERM", "SIGSTKFLT", "SIGCHLD", "SIGCONT", "SIGSTOP",
-	"SIGTSTP", "SIGTTIN", "SIGTTOU", "SIGURG", "SIGXCPU",
-	"SIGXFSZ", "SIGVTALRM", "SIGPROF", "SIGWINCH", "SIGPOLL",
-	"SIGPWR", "SIGSYS",
-}
-
-// sigName returns the symbolic name for the given signal number.  If
-// the signal number is invalid, returns "<invalid>".
-func sigName(signal int) string {
-	if signal < 0 || signal >= len(sigNames) {
-		return "<invalid>"
-	}
-	return sigNames[signal]
-}
-
-func (t *thread) Stopped() (Cause, os.Error) {
-	var c Cause
-	err := t.proc.do(func() os.Error {
-		switch t.state {
-		case stopped:
-			c = Stopped{}
-
-		case stoppedBreakpoint:
-			c = Breakpoint(t.breakpoint.pc)
-
-		case stoppedSignal:
-			c = Signal(sigName(t.signal))
-
-		case stoppedThreadCreate:
-			c = &ThreadCreate{t.newThread}
-
-		case stoppedExiting, exiting, exited:
-			if t.signal == -1 {
-				c = &ThreadExit{t.exitStatus, ""}
-			} else {
-				c = &ThreadExit{t.exitStatus, sigName(t.signal)}
-			}
-
-		default:
-			return &badState{t, "cannot get stop cause", t.state}
-		}
-		return nil
-	})
-	if err != nil {
-		return nil, err
-	}
-
-	return c, nil
-}
-
-func (p *process) Threads() []Thread {
-	var res []Thread
-
-	p.do(func() os.Error {
-		res = make([]Thread, len(p.threads))
-		i := 0
-		for _, t := range p.threads {
-			// Exclude zombie threads.
-			st := t.state
-			if st == exiting || st == exited || st == detached {
-				continue
-			}
-
-			res[i] = t
-			i++
-		}
-		res = res[0:i]
-		return nil
-	})
-	return res
-}
-
-func (p *process) AddBreakpoint(pc Word) os.Error {
-	return p.do(func() os.Error {
-		if t := p.someRunningThread(); t != nil {
-			return &badState{t, "cannot add breakpoint", t.state}
-		}
-		if _, ok := p.breakpoints[uintptr(pc)]; ok {
-			return breakpointExistsError(pc)
-		}
-		p.breakpoints[uintptr(pc)] = &breakpoint{pc: uintptr(pc)}
-		return nil
-	})
-}
-
-func (p *process) RemoveBreakpoint(pc Word) os.Error {
-	return p.do(func() os.Error {
-		if t := p.someRunningThread(); t != nil {
-			return &badState{t, "cannot remove breakpoint", t.state}
-		}
-		if _, ok := p.breakpoints[uintptr(pc)]; !ok {
-			return noBreakpointError(pc)
-		}
-		p.breakpoints[uintptr(pc)] = nil, false
-		return nil
-	})
-}
-
-func (p *process) Continue() os.Error {
-	// Single step any threads that are stopped at breakpoints so
-	// we can reinstall breakpoints.
-	var ready chan os.Error
-	count := 0
-
-	err := p.do(func() os.Error {
-		// We make the ready channel big enough to hold all
-		// ready message so we don't jam up the monitor if we
-		// stop listening (e.g., if there's an error).
-		ready = make(chan os.Error, len(p.threads))
-
-		for _, t := range p.threads {
-			if !t.state.isStopped() {
-				continue
-			}
-
-			// We use the breakpoint map directly here
-			// instead of checking the stop cause because
-			// it could have been stopped at a breakpoint
-			// for some other reason, or the breakpoint
-			// could have been added since it was stopped.
-			var regs syscall.PtraceRegs
-			err := t.ptraceGetRegs(&regs)
-			if err != nil {
-				return err
-			}
-			if b, ok := p.breakpoints[uintptr(regs.PC())]; ok {
-				t.logTrace("stepping over breakpoint %v", b)
-				if err := t.stepAsync(ready); err != nil {
-					return err
-				}
-				count++
-			}
-		}
-		return nil
-	})
-	if err != nil {
-		p.stopMonitor(err)
-		return err
-	}
-
-	// Wait for single stepping threads
-	for count > 0 {
-		err = <-ready
-		if err != nil {
-			p.stopMonitor(err)
-			return err
-		}
-		count--
-	}
-
-	// Continue all threads
-	err = p.do(func() os.Error {
-		if err := p.installBreakpoints(); err != nil {
-			return err
-		}
-
-		for _, t := range p.threads {
-			var err os.Error
-			switch {
-			case !t.state.isStopped():
-				continue
-
-			case t.state == stoppedSignal && t.signal != syscall.SIGSTOP && t.signal != syscall.SIGTRAP:
-				t.logTrace("continuing with signal %d", t.signal)
-				err = t.ptraceContWithSignal(t.signal)
-
-			default:
-				t.logTrace("continuing")
-				err = t.ptraceCont()
-			}
-			if err != nil {
-				return err
-			}
-			if t.state == stoppedExiting {
-				t.setState(exiting)
-			} else {
-				t.setState(running)
-			}
-		}
-		return nil
-	})
-	if err != nil {
-		// TODO(austin) Do we need to stop the monitor with
-		// this error atomically with the do-routine above?
-		p.stopMonitor(err)
-		return err
-	}
-
-	return nil
-}
-
-func (p *process) WaitStop() os.Error {
-	// We need a non-blocking ready channel for the case where all
-	// threads are already stopped.
-	ready := make(chan os.Error, 1)
-
-	err := p.do(func() os.Error {
-		// Are all of the threads already stopped?
-		if p.someRunningThread() == nil {
-			ready <- nil
-			return nil
-		}
-
-		// Monitor state transitions
-		h := &transitionHandler{}
-		h.handle = func(st *thread, old, new threadState) {
-			if !new.isRunning() {
-				if p.someRunningThread() == nil {
-					ready <- nil
-					return
-				}
-			}
-			p.transitionHandlers.Push(h)
-		}
-		h.onErr = func(err os.Error) { ready <- err }
-		p.transitionHandlers.Push(h)
-		return nil
-	})
-	if err != nil {
-		return err
-	}
-
-	return <-ready
-}
-
-func (p *process) Stop() os.Error {
-	err := p.do(func() os.Error { return p.stopAsync() })
-	if err != nil {
-		return err
-	}
-
-	return p.WaitStop()
-}
-
-func (p *process) Detach() os.Error {
-	if err := p.Stop(); err != nil {
-		return err
-	}
-
-	err := p.do(func() os.Error {
-		if err := p.uninstallBreakpoints(); err != nil {
-			return err
-		}
-
-		for pid, t := range p.threads {
-			if t.state.isStopped() {
-				// We can't detach from zombies.
-				if err := t.ptraceDetach(); err != nil {
-					return err
-				}
-			}
-			t.setState(detached)
-			p.threads[pid] = nil, false
-		}
-		return nil
-	})
-	// TODO(austin) Wait for monitor thread to exit?
-	return err
-}
-
-// newThread creates a new thread object and waits for its initial
-// signal.  If cloned is true, this thread was cloned from a thread we
-// are already attached to.
-//
-// Must be run from the monitor thread.
-func (p *process) newThread(tid int, signal int, cloned bool) (*thread, os.Error) {
-	t := &thread{tid: tid, proc: p, state: stopped}
-
-	// Get the signal from the thread
-	// TODO(austin) Thread might already be stopped if we're attaching.
-	w, err := os.Wait(tid, syscall.WALL)
-	if err != nil {
-		return nil, err
-	}
-	if w.Pid != tid || w.StopSignal() != signal {
-		return nil, &newThreadError{w, tid, signal}
-	}
-
-	if !cloned {
-		err = t.ptraceSetOptions(syscall.PTRACE_O_TRACECLONE | syscall.PTRACE_O_TRACEEXIT)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	p.threads[tid] = t
-
-	return t, nil
-}
-
-// attachThread attaches a running thread to the process.
-//
-// Must NOT be run from the monitor thread.
-func (p *process) attachThread(tid int) (*thread, os.Error) {
-	p.logTrace("attaching to thread %d", tid)
-	var thr *thread
-	err := p.do(func() os.Error {
-		errno := syscall.PtraceAttach(tid)
-		if errno != 0 {
-			return os.NewSyscallError("ptrace(ATTACH)", errno)
-		}
-
-		var err os.Error
-		thr, err = p.newThread(tid, syscall.SIGSTOP, false)
-		return err
-	})
-	return thr, err
-}
-
-// attachAllThreads attaches to all threads in a process.
-func (p *process) attachAllThreads() os.Error {
-	taskPath := "/proc/" + strconv.Itoa(p.pid) + "/task"
-	taskDir, err := os.Open(taskPath)
-	if err != nil {
-		return err
-	}
-	defer taskDir.Close()
-
-	// We stop threads as we attach to them; however, because new
-	// threads can appear while we're looping over all of them, we
-	// have to repeatedly scan until we know we're attached to all
-	// of them.
-	for again := true; again; {
-		again = false
-
-		tids, err := taskDir.Readdirnames(-1)
-		if err != nil {
-			return err
-		}
-
-		for _, tidStr := range tids {
-			tid, err := strconv.Atoi(tidStr)
-			if err != nil {
-				return err
-			}
-			if _, ok := p.threads[tid]; ok {
-				continue
-			}
-
-			_, err = p.attachThread(tid)
-			if err != nil {
-				// There could have been a race, or
-				// this process could be a zombie.
-				statFile, err2 := ioutil.ReadFile(taskPath + "/" + tidStr + "/stat")
-				if err2 != nil {
-					switch err2 := err2.(type) {
-					case *os.PathError:
-						if err2.Error == os.ENOENT {
-							// Raced with thread exit
-							p.logTrace("raced with thread %d exit", tid)
-							continue
-						}
-					}
-					// Return the original error
-					return err
-				}
-
-				statParts := strings.SplitN(string(statFile), " ", 4)
-				if len(statParts) > 2 && statParts[2] == "Z" {
-					// tid is a zombie
-					p.logTrace("thread %d is a zombie", tid)
-					continue
-				}
-
-				// Return the original error
-				return err
-			}
-			again = true
-		}
-	}
-
-	return nil
-}
-
-// newProcess creates a new process object and starts its monitor thread.
-func newProcess(pid int) *process {
-	p := &process{
-		pid:         pid,
-		threads:     make(map[int]*thread),
-		breakpoints: make(map[uintptr]*breakpoint),
-		ready:       make(chan bool, 1),
-		debugEvents: make(chan *debugEvent),
-		debugReqs:   make(chan *debugReq),
-		stopReq:     make(chan os.Error),
-	}
-
-	go p.monitor()
-
-	return p
-}
-
-// Attach attaches to process pid and stops all of its threads.
-func Attach(pid int) (Process, os.Error) {
-	p := newProcess(pid)
-
-	// Attach to all threads
-	err := p.attachAllThreads()
-	if err != nil {
-		p.Detach()
-		// TODO(austin) Detach stopped the monitor already
-		//p.stopMonitor(err);
-		return nil, err
-	}
-
-	return p, nil
-}
-
-// StartProcess forks the current process and execs argv0, stopping the
-// new process after the exec syscall.  See os.StartProcess for additional
-// details.
-func StartProcess(argv0 string, argv []string, attr *os.ProcAttr) (Process, os.Error) {
-	sysattr := &syscall.ProcAttr{
-		Dir: attr.Dir,
-		Env: attr.Env,
-		Sys: &syscall.SysProcAttr{
-			Ptrace: true,
-		},
-	}
-	p := newProcess(-1)
-
-	// Create array of integer (system) fds.
-	intfd := make([]int, len(attr.Files))
-	for i, f := range attr.Files {
-		if f == nil {
-			intfd[i] = -1
-		} else {
-			intfd[i] = f.Fd()
-		}
-	}
-	sysattr.Files = intfd
-
-	// Fork from the monitor thread so we get the right tracer pid.
-	err := p.do(func() os.Error {
-		pid, _, errno := syscall.StartProcess(argv0, argv, sysattr)
-		if errno != 0 {
-			return &os.PathError{"fork/exec", argv0, os.Errno(errno)}
-		}
-		p.pid = pid
-
-		// The process will raise SIGTRAP when it reaches execve.
-		_, err := p.newThread(pid, syscall.SIGTRAP, false)
-		return err
-	})
-	if err != nil {
-		p.stopMonitor(err)
-		return nil, err
-	}
-
-	return p, nil
-}
diff --git a/src/pkg/debug/proc/proc_windows.go b/src/pkg/debug/proc/proc_windows.go
deleted file mode 100644
index 661474b67aa..00000000000
--- a/src/pkg/debug/proc/proc_windows.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import "os"
-
-// Process tracing is not supported on windows yet.
-
-func Attach(pid int) (Process, os.Error) {
-	return nil, os.NewError("debug/proc not implemented on windows")
-}
-
-func StartProcess(argv0 string, argv []string, attr *os.ProcAttr) (Process, os.Error) {
-	return Attach(0)
-}
diff --git a/src/pkg/debug/proc/ptrace-nptl.txt b/src/pkg/debug/proc/ptrace-nptl.txt
deleted file mode 100644
index 62cbf770035..00000000000
--- a/src/pkg/debug/proc/ptrace-nptl.txt
+++ /dev/null
@@ -1,132 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-ptrace and NTPL, the missing manpage
-
-== Signals ==
-
-A signal sent to a ptrace'd process or thread causes only the thread
-that receives it to stop and report to the attached process.
-
-Use tgkill to target a signal (for example, SIGSTOP) at a particular
-thread.  If you use kill, the signal could be delivered to another
-thread in the same process.
-
-Note that SIGSTOP differs from its usual behavior when a process is
-being traced.  Usually, a SIGSTOP sent to any thread in a thread group
-will stop all threads in the thread group.  When a thread is traced,
-however, a SIGSTOP affects only the receiving thread (and any other
-threads in the thread group that are not traced).
-
-SIGKILL behaves like it does for non-traced processes.  It affects all
-threads in the process and terminates them without the WSTOPSIG event
-generated by other signals.  However, if PTRACE_O_TRACEEXIT is set,
-the attached process will still receive PTRACE_EVENT_EXIT events
-before receiving WIFSIGNALED events.
-
-See "Following thread death" for a caveat regarding signal delivery to
-zombie threads.
-
-== Waiting on threads ==
-
-Cloned threads in ptrace'd processes are treated similarly to cloned
-threads in your own process.  Thus, you must use the __WALL option in
-order to receive notifications from threads created by the child
-process.  Similarly, the __WCLONE option will wait only on
-notifications from threads created by the child process and *not* on
-notifications from the initial child thread.
-
-Even when waiting on a specific thread's PID using waitpid or similar,
-__WALL or __WCLONE is necessary or waitpid will return ECHILD.
-
-== Attaching to existing threads ==
-
-libthread_db (which gdb uses), attaches to existing threads by pulling
-the pthread data structures out of the traced process.  The much
-easier way is to traverse the /proc/PID/task directory, though it's
-unclear how the semantics of these two approaches differ.
-
-Unfortunately, if the main thread has exited (but the overall process
-has not), it sticks around as a zombie process.  This zombie will
-appear in the /proc/PID/task directory, but trying to attach to it
-will yield EPERM.  In this case, the third field of the
-/proc/PID/task/PID/stat file will be "Z".  Attempting to open the stat
-file is also a convenient way to detect races between listing the task
-directory and the thread exiting.  Coincidentally, gdb will simply
-fail to attach to a process whose main thread is a zombie.
-
-Because new threads may be created while the debugger is in the
-process of attaching to existing threads, the debugger must repeatedly
-re-list the task directory until it has attached to (and thus stopped)
-every thread listed.
-
-In order to follow new threads created by existing threads,
-PTRACE_O_TRACECLONE must be set on each thread attached to.
-
-== Following new threads ==
-
-With the child process stopped, use PTRACE_SETOPTIONS to set the
-PTRACE_O_TRACECLONE option.  This option is per-thread, and thus must
-be set on each existing thread individually.  When an existing thread
-with PTRACE_O_TRACECLONE set spawns a new thread, the existing thread
-will stop with (SIGTRAP | PTRACE_EVENT_CLONE << 8) and the PID of the
-new thread can be retrieved with PTRACE_GETEVENTMSG on the creating
-thread.  At this time, the new thread will exist, but will initially
-be stopped with a SIGSTOP.  The new thread will automatically be
-traced and will inherit the PTRACE_O_TRACECLONE option from its
-parent.  The attached process should wait on the new thread to receive
-the SIGSTOP notification.
-
-When using waitpid(-1, ...), don't rely on the parent thread reporting
-a SIGTRAP before receiving the SIGSTOP from the new child thread.
-
-Without PTRACE_O_TRACECLONE, newly cloned threads will not be
-ptrace'd.  As a result, signals received by new threads will be
-handled in the usual way, which may affect the parent and in turn
-appear to the attached process, but attributed to the parent (possibly
-in unexpected ways).
-
-== Following thread death ==
-
-If any thread with the PTRACE_O_TRACEEXIT option set exits (either by
-returning or pthread_exit'ing), the tracing process will receive an
-immediate PTRACE_EVENT_EXIT.  At this point, the thread will still
-exist.  The exit status, encoded as for wait, can be queried using
-PTRACE_GETEVENTMSG on the exiting thread's PID.  The thread should be
-continued so it can actually exit, after which its wait behavior is
-the same as for a thread without the PTRACE_O_TRACEEXIT option.
-
-If a non-main thread exits (either by returning or pthread_exit'ing),
-its corresponding process will also exit, producing a WIFEXITED event
-(after the process is continued from a possible PTRACE_EVENT_EXIT
-event).  It is *not* necessary for another thread to ptrace_join for
-this to happen.
-
-If the main thread exits by returning, then all threads will exit,
-first generating a PTRACE_EVENT_EXIT event for each thread if
-appropriate, then producing a WIFEXITED event for each thread.
-
-If the main thread exits using pthread_exit, then it enters a
-non-waitable zombie state.  It will still produce an immediate
-PTRACE_O_TRACEEXIT event, but the WIFEXITED event will be delayed
-until the entire process exits.  This state exists so that shells
-don't think the process is done until all of the threads have exited.
-Unfortunately, signals cannot be delivered to non-waitable zombies.
-Most notably, SIGSTOP cannot be delivered; as a result, when you
-broadcast SIGSTOP to all of the threads, you must not wait for
-non-waitable zombies to stop.  Furthermore, any ptrace command on a
-non-waitable zombie, including PTRACE_DETACH, will return ESRCH.
-
-== Multi-threaded debuggers ==
-
-If the debugger itself is multi-threaded, ptrace calls must come from
-the same thread that originally attached to the remote thread.  The
-kernel simply compares the PID of the caller of ptrace against the
-tracer PID of the process passed to ptrace.  Because each debugger
-thread has a different PID, calling ptrace from a different thread
-might as well be calling it from a different process and the kernel
-will return ESRCH.
-
-wait, on the other hand, does not have this restriction.  Any debugger
-thread can wait on any thread in the attached process.
diff --git a/src/pkg/debug/proc/regs_darwin_386.go b/src/pkg/debug/proc/regs_darwin_386.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_darwin_386.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
diff --git a/src/pkg/debug/proc/regs_darwin_amd64.go b/src/pkg/debug/proc/regs_darwin_amd64.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_darwin_amd64.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
diff --git a/src/pkg/debug/proc/regs_freebsd_386.go b/src/pkg/debug/proc/regs_freebsd_386.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_freebsd_386.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
diff --git a/src/pkg/debug/proc/regs_freebsd_amd64.go b/src/pkg/debug/proc/regs_freebsd_amd64.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_freebsd_amd64.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
diff --git a/src/pkg/debug/proc/regs_linux_386.go b/src/pkg/debug/proc/regs_linux_386.go
deleted file mode 100644
index b4a9769db55..00000000000
--- a/src/pkg/debug/proc/regs_linux_386.go
+++ /dev/null
@@ -1,143 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import (
-	"os"
-	"strconv"
-	"syscall"
-)
-
-type _386Regs struct {
-	syscall.PtraceRegs
-	setter func(*syscall.PtraceRegs) os.Error
-}
-
-var names = []string{
-	"eax",
-	"ebx",
-	"ecx",
-	"edx",
-	"esi",
-	"edi",
-	"ebp",
-	"esp",
-	"eip",
-	"eflags",
-	"cs",
-	"ss",
-	"ds",
-	"es",
-	"fs",
-	"gs",
-}
-
-func (r *_386Regs) PC() Word { return Word(r.Eip) }
-
-func (r *_386Regs) SetPC(val Word) os.Error {
-	r.Eip = int32(val)
-	return r.setter(&r.PtraceRegs)
-}
-
-func (r *_386Regs) Link() Word {
-	// TODO(austin)
-	panic("No link register")
-}
-
-func (r *_386Regs) SetLink(val Word) os.Error { panic("No link register") }
-
-func (r *_386Regs) SP() Word { return Word(r.Esp) }
-
-func (r *_386Regs) SetSP(val Word) os.Error {
-	r.Esp = int32(val)
-	return r.setter(&r.PtraceRegs)
-}
-
-func (r *_386Regs) Names() []string { return names }
-
-func (r *_386Regs) Get(i int) Word {
-	switch i {
-	case 0:
-		return Word(uint32(r.Eax))
-	case 1:
-		return Word(uint32(r.Ebx))
-	case 2:
-		return Word(uint32(r.Ecx))
-	case 3:
-		return Word(uint32(r.Edx))
-	case 4:
-		return Word(uint32(r.Esi))
-	case 5:
-		return Word(uint32(r.Edi))
-	case 6:
-		return Word(uint32(r.Ebp))
-	case 7:
-		return Word(uint32(r.Esp))
-	case 8:
-		return Word(uint32(r.Eip))
-	case 9:
-		return Word(uint32(r.Eflags))
-	case 10:
-		return Word(r.Xcs)
-	case 11:
-		return Word(r.Xss)
-	case 12:
-		return Word(r.Xds)
-	case 13:
-		return Word(r.Xes)
-	case 14:
-		return Word(r.Xfs)
-	case 15:
-		return Word(r.Xgs)
-	}
-	panic("invalid register index " + strconv.Itoa(i))
-}
-
-func (r *_386Regs) Set(i int, val Word) os.Error {
-	switch i {
-	case 0:
-		r.Eax = int32(val)
-	case 1:
-		r.Ebx = int32(val)
-	case 2:
-		r.Ecx = int32(val)
-	case 3:
-		r.Edx = int32(val)
-	case 4:
-		r.Esi = int32(val)
-	case 5:
-		r.Edi = int32(val)
-	case 6:
-		r.Ebp = int32(val)
-	case 7:
-		r.Esp = int32(val)
-	case 8:
-		r.Eip = int32(val)
-	case 9:
-		r.Eflags = int32(val)
-	case 10:
-		r.Xcs = int32(val)
-	case 11:
-		r.Xss = int32(val)
-	case 12:
-		r.Xds = int32(val)
-	case 13:
-		r.Xes = int32(val)
-	case 14:
-		r.Xfs = int32(val)
-	case 15:
-		r.Xgs = int32(val)
-	default:
-		panic("invalid register index " + strconv.Itoa(i))
-	}
-	return r.setter(&r.PtraceRegs)
-}
-
-func newRegs(regs *syscall.PtraceRegs, setter func(*syscall.PtraceRegs) os.Error) Regs {
-	res := _386Regs{}
-	res.PtraceRegs = *regs
-	res.setter = setter
-	return &res
-}
diff --git a/src/pkg/debug/proc/regs_linux_amd64.go b/src/pkg/debug/proc/regs_linux_amd64.go
deleted file mode 100644
index 381be29b179..00000000000
--- a/src/pkg/debug/proc/regs_linux_amd64.go
+++ /dev/null
@@ -1,191 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import (
-	"os"
-	"strconv"
-	"syscall"
-)
-
-type amd64Regs struct {
-	syscall.PtraceRegs
-	setter func(*syscall.PtraceRegs) os.Error
-}
-
-var names = [...]string{
-	"rax",
-	"rbx",
-	"rcx",
-	"rdx",
-	"rsi",
-	"rdi",
-	"rbp",
-	"rsp",
-	"r8",
-	"r9",
-	"r10",
-	"r11",
-	"r12",
-	"r13",
-	"r14",
-	"r15",
-	"rip",
-	"eflags",
-	"cs",
-	"ss",
-	"ds",
-	"es",
-	"fs",
-	"gs",
-
-	// PtraceRegs contains these registers, but I don't think
-	// they're actually meaningful.
-	//"orig_rax",
-	//"fs_base",
-	//"gs_base",
-}
-
-func (r *amd64Regs) PC() Word { return Word(r.Rip) }
-
-func (r *amd64Regs) SetPC(val Word) os.Error {
-	r.Rip = uint64(val)
-	return r.setter(&r.PtraceRegs)
-}
-
-func (r *amd64Regs) Link() Word {
-	// TODO(austin)
-	panic("No link register")
-}
-
-func (r *amd64Regs) SetLink(val Word) os.Error {
-	panic("No link register")
-}
-
-func (r *amd64Regs) SP() Word { return Word(r.Rsp) }
-
-func (r *amd64Regs) SetSP(val Word) os.Error {
-	r.Rsp = uint64(val)
-	return r.setter(&r.PtraceRegs)
-}
-
-func (r *amd64Regs) Names() []string { return names[0:] }
-
-func (r *amd64Regs) Get(i int) Word {
-	switch i {
-	case 0:
-		return Word(r.Rax)
-	case 1:
-		return Word(r.Rbx)
-	case 2:
-		return Word(r.Rcx)
-	case 3:
-		return Word(r.Rdx)
-	case 4:
-		return Word(r.Rsi)
-	case 5:
-		return Word(r.Rdi)
-	case 6:
-		return Word(r.Rbp)
-	case 7:
-		return Word(r.Rsp)
-	case 8:
-		return Word(r.R8)
-	case 9:
-		return Word(r.R9)
-	case 10:
-		return Word(r.R10)
-	case 11:
-		return Word(r.R11)
-	case 12:
-		return Word(r.R12)
-	case 13:
-		return Word(r.R13)
-	case 14:
-		return Word(r.R14)
-	case 15:
-		return Word(r.R15)
-	case 16:
-		return Word(r.Rip)
-	case 17:
-		return Word(r.Eflags)
-	case 18:
-		return Word(r.Cs)
-	case 19:
-		return Word(r.Ss)
-	case 20:
-		return Word(r.Ds)
-	case 21:
-		return Word(r.Es)
-	case 22:
-		return Word(r.Fs)
-	case 23:
-		return Word(r.Gs)
-	}
-	panic("invalid register index " + strconv.Itoa(i))
-}
-
-func (r *amd64Regs) Set(i int, val Word) os.Error {
-	switch i {
-	case 0:
-		r.Rax = uint64(val)
-	case 1:
-		r.Rbx = uint64(val)
-	case 2:
-		r.Rcx = uint64(val)
-	case 3:
-		r.Rdx = uint64(val)
-	case 4:
-		r.Rsi = uint64(val)
-	case 5:
-		r.Rdi = uint64(val)
-	case 6:
-		r.Rbp = uint64(val)
-	case 7:
-		r.Rsp = uint64(val)
-	case 8:
-		r.R8 = uint64(val)
-	case 9:
-		r.R9 = uint64(val)
-	case 10:
-		r.R10 = uint64(val)
-	case 11:
-		r.R11 = uint64(val)
-	case 12:
-		r.R12 = uint64(val)
-	case 13:
-		r.R13 = uint64(val)
-	case 14:
-		r.R14 = uint64(val)
-	case 15:
-		r.R15 = uint64(val)
-	case 16:
-		r.Rip = uint64(val)
-	case 17:
-		r.Eflags = uint64(val)
-	case 18:
-		r.Cs = uint64(val)
-	case 19:
-		r.Ss = uint64(val)
-	case 20:
-		r.Ds = uint64(val)
-	case 21:
-		r.Es = uint64(val)
-	case 22:
-		r.Fs = uint64(val)
-	case 23:
-		r.Gs = uint64(val)
-	default:
-		panic("invalid register index " + strconv.Itoa(i))
-	}
-	return r.setter(&r.PtraceRegs)
-}
-
-func newRegs(regs *syscall.PtraceRegs, setter func(*syscall.PtraceRegs) os.Error) Regs {
-	res := amd64Regs{}
-	res.PtraceRegs = *regs
-	res.setter = setter
-	return &res
-}
diff --git a/src/pkg/debug/proc/regs_linux_arm.go b/src/pkg/debug/proc/regs_linux_arm.go
deleted file mode 100644
index ec78cbcf259..00000000000
--- a/src/pkg/debug/proc/regs_linux_arm.go
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
-
-import (
-	"os"
-	"syscall"
-)
-
-// TODO(kaib): add support
-
-type armRegs struct{}
-
-func (r *armRegs) PC() Word { return Word(0) }
-
-func (r *armRegs) SetPC(val Word) os.Error { return nil }
-
-func (r *armRegs) Link() Word { return Word(0) }
-
-func (r *armRegs) SetLink(val Word) os.Error { return nil }
-
-func (r *armRegs) SP() Word { return Word(0) }
-
-func (r *armRegs) SetSP(val Word) os.Error { return nil }
-
-func (r *armRegs) Names() []string { return nil }
-
-func (r *armRegs) Get(i int) Word { return Word(0) }
-
-func (r *armRegs) Set(i int, val Word) os.Error {
-	return nil
-}
-
-func newRegs(regs *syscall.PtraceRegs, setter func(*syscall.PtraceRegs) os.Error) Regs {
-	res := armRegs{}
-	return &res
-}
diff --git a/src/pkg/debug/proc/regs_windows_386.go b/src/pkg/debug/proc/regs_windows_386.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_windows_386.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc
diff --git a/src/pkg/debug/proc/regs_windows_amd64.go b/src/pkg/debug/proc/regs_windows_amd64.go
deleted file mode 100644
index 60c9ac719e9..00000000000
--- a/src/pkg/debug/proc/regs_windows_amd64.go
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package proc