Reorganisation of the source tree

Most of the other users of the fptools build system have migrated to
Cabal, and with the move to darcs we can now flatten the source tree
without losing history, so here goes.

The main change is that the ghc/ subdir is gone, and most of what it
contained is now at the top level.  The build system now makes no
pretense at being multi-project, it is just the GHC build system.

No doubt this will break many things, and there will be a period of
instability while we fix the dependencies.  A straightforward build
should work, but I haven't yet fixed binary/source distributions.
Changes to the Building Guide will follow, too.

8 files changed, 1393 insertions, 0 deletions

diff --git a/rts/posix/GetTime.c b/rts/posix/GetTime.c
new file mode 100644
index 0000000000..3a0764cb91
--- /dev/null
+++ b/rts/posix/GetTime.c
@@ -0,0 +1,141 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team 2005
+ *
+ * Machine-dependent time measurement functions
+ *
+ * ---------------------------------------------------------------------------*/
+
+// Not POSIX, due to use of ru_majflt in getPageFaults()
+// #include "PosixSource.h"
+
+#include "Rts.h"
+#include "GetTime.h"
+
+#ifdef HAVE_TIME_H
+# include <time.h>
+#endif
+
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+
+#if HAVE_SYS_RESOURCE_H
+# include <sys/resource.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifdef HAVE_SYS_TIMES_H
+# include <sys/times.h>
+#endif
+
+#if ! ((defined(HAVE_GETRUSAGE) && !irix_HOST_OS) || defined(HAVE_TIMES))
+#error No implementation for getProcessCPUTime() available.
+#endif
+
+#if defined(HAVE_GETTIMEOFDAY) && defined(HAVE_GETRUSAGE) && !irix_HOST_OS
+// we'll implement getProcessCPUTime() and getProcessElapsedTime()
+// separately, using getrusage() and gettimeofday() respectively
+
+Ticks getProcessCPUTime(void)
+{
+    struct rusage t;
+    getrusage(RUSAGE_SELF, &t);
+    return (t.ru_utime.tv_sec * TICKS_PER_SECOND + 
+	    ((Ticks)t.ru_utime.tv_usec * TICKS_PER_SECOND)/1000000);
+}
+
+Ticks getProcessElapsedTime(void)
+{
+    struct timeval tv;
+    gettimeofday(&tv, (struct timezone *) NULL);
+    return (tv.tv_sec * TICKS_PER_SECOND +
+	    ((Ticks)tv.tv_usec * TICKS_PER_SECOND)/1000000);
+}
+
+void getProcessTimes(Ticks *user, Ticks *elapsed)
+{
+    *user    = getProcessCPUTime();
+    *elapsed = getProcessElapsedTime();
+}
+
+#elif defined(HAVE_TIMES)
+
+// we'll use the old times() API.
+
+Ticks getProcessCPUTime(void)
+{
+    Ticks user, elapsed;
+    getProcessTimes(&user,&elapsed);
+    return user;
+}
+
+Ticks getProcessElapsedTime(void)
+{
+    Ticks user, elapsed;
+    getProcessTimes(&user,&elapsed);
+    return elapsed;
+}
+
+void getProcessTimes(Ticks *user, Ticks *elapsed)
+{
+    static nat ClockFreq = 0;
+
+    if (ClockFreq == 0) {
+#if defined(HAVE_SYSCONF)
+	long ticks;
+	ticks = sysconf(_SC_CLK_TCK);
+	if ( ticks == -1 ) {
+	    errorBelch("sysconf\n");
+	    stg_exit(EXIT_FAILURE);
+	}
+	ClockFreq = ticks;
+#elif defined(CLK_TCK)		/* defined by POSIX */
+	ClockFreq = CLK_TCK;
+#elif defined(HZ)
+	ClockFreq = HZ;
+#elif defined(CLOCKS_PER_SEC)
+	ClockFreq = CLOCKS_PER_SEC;
+#else
+	errorBelch("can't get clock resolution");
+	stg_exit(EXIT_FAILURE);
+#endif
+    }
+
+    struct tms t;
+    clock_t r = times(&t);
+    *user = (((Ticks)t.tms_utime * TICKS_PER_SECOND) / ClockFreq);
+    *elapsed = (((Ticks)r * TICKS_PER_SECOND) / ClockFreq);
+}
+
+#endif // HAVE_TIMES
+
+Ticks getThreadCPUTime(void)
+{
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_THREAD_CPUTIME_ID)
+    // clock_gettime() gives us per-thread CPU time.  It isn't
+    // reliable on Linux, but it's the best we have.
+    struct timespec ts;
+    clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
+    return (ts.tv_sec * TICKS_PER_SECOND + 
+	    ((Ticks)ts.tv_nsec * TICKS_PER_SECOND) / 1000000000);
+#else
+    return getProcessCPUTime();
+#endif
+}
+
+nat
+getPageFaults(void)
+{
+#if !defined(HAVE_GETRUSAGE) || irix_HOST_OS
+    return 0;
+#else
+    struct rusage t;
+    getrusage(RUSAGE_SELF, &t);
+    return(t.ru_majflt);
+#endif
+}
+
diff --git a/rts/posix/Itimer.c b/rts/posix/Itimer.c
new file mode 100644
index 0000000000..83ed84d6ef
--- /dev/null
+++ b/rts/posix/Itimer.c
@@ -0,0 +1,226 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1995-1999
+ *
+ * Interval timer for profiling and pre-emptive scheduling.
+ *
+ * ---------------------------------------------------------------------------*/
+
+/*
+ * The interval timer is used for profiling and for context switching in the
+ * threaded build.  Though POSIX 1003.1b includes a standard interface for
+ * such things, no one really seems to be implementing them yet.  Even 
+ * Solaris 2.3 only seems to provide support for @CLOCK_REAL@, whereas we're
+ * keen on getting access to @CLOCK_VIRTUAL@.
+ * 
+ * Hence, we use the old-fashioned @setitimer@ that just about everyone seems
+ * to support.  So much for standards.
+ */
+#include "Rts.h"
+#include "RtsFlags.h"
+#include "Timer.h"
+#include "Ticker.h"
+#include "posix/Itimer.h"
+#include "Proftimer.h"
+#include "Schedule.h"
+#include "posix/Select.h"
+
+/* As recommended in the autoconf manual */
+# ifdef TIME_WITH_SYS_TIME
+#  include <sys/time.h>
+#  include <time.h>
+# else
+#  ifdef HAVE_SYS_TIME_H
+#   include <sys/time.h>
+#  else
+#   include <time.h>
+#  endif
+# endif
+
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+/* Major bogosity:
+ * 
+ * In the threaded RTS, we can't set the virtual timer because the
+ * thread which has the virtual timer might be sitting waiting for a
+ * capability, and the virtual timer only ticks in CPU time.
+ *
+ * So, possible solutions:
+ *
+ * (1) tick in realtime.  Not very good, because this ticker is used for
+ *     profiling, and this will give us unreliable time profiling
+ *     results.  Furthermore, this requires picking a single OS thread
+ *     to be the timekeeper, which is a bad idea because the thread in
+ *     question might just be making a temporary call into Haskell land.
+ *
+ * (2) save/restore the virtual timer around excursions into STG land.
+ *     Sounds great, but I tried it and the resolution of the virtual timer
+ *     isn't good enough (on Linux) - most of our excursions fall
+ *     within the timer's resolution and we never make any progress.
+ *   
+ * (3) have a virtual timer in every OS thread.  Might be reasonable,
+ *     because most of the time there is only ever one of these
+ *     threads running, so it approximates a single virtual timer.
+ *     But still quite bogus (and I got crashes when I tried this).
+ *
+ * For now, we're using (1), but this needs a better solution. --SDM
+ */
+#ifdef THREADED_RTS
+#define ITIMER_FLAVOUR  ITIMER_REAL
+#define ITIMER_SIGNAL   SIGALRM
+#else
+#define ITIMER_FLAVOUR  ITIMER_VIRTUAL
+#define ITIMER_SIGNAL   SIGVTALRM
+#endif
+
+static
+int
+install_vtalrm_handler(TickProc handle_tick)
+{
+    struct sigaction action;
+
+    action.sa_handler = handle_tick;
+
+    sigemptyset(&action.sa_mask);
+
+#ifdef SA_RESTART
+    // specify SA_RESTART.  One consequence if we don't do this is
+    // that readline gets confused by the -threaded RTS.  It seems
+    // that if a SIGALRM handler is installed without SA_RESTART,
+    // readline installs its own SIGALRM signal handler (see
+    // readline's signals.c), and this somehow causes readline to go
+    // wrong when the input exceeds a single line (try it).
+    action.sa_flags = SA_RESTART;
+#else
+    action.sa_flags = 0;
+#endif
+
+    return sigaction(ITIMER_SIGNAL, &action, NULL);
+}
+
+int
+startTicker(nat ms, TickProc handle_tick)
+{
+# ifndef HAVE_SETITIMER
+  /*    debugBelch("No virtual timer on this system\n"); */
+    return -1;
+# else
+    struct itimerval it;
+
+    install_vtalrm_handler(handle_tick);
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    it.it_value.tv_sec = ms / 1000;
+    it.it_value.tv_usec = 1000 * (ms - (1000 * it.it_value.tv_sec));
+    it.it_interval = it.it_value;
+    return (setitimer(ITIMER_FLAVOUR, &it, NULL));
+# endif
+}
+
+int
+stopTicker()
+{
+# ifndef HAVE_SETITIMER
+  /*    debugBelch("No virtual timer on this system\n"); */
+    return -1;
+# else
+    struct itimerval it;
+  
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_usec = 0;
+    it.it_interval = it.it_value;
+    return (setitimer(ITIMER_FLAVOUR, &it, NULL));
+# endif
+}
+
+# if 0
+/* This is a potential POSIX version */
+int
+startTicker(nat ms)
+{
+    struct sigevent se;
+    struct itimerspec it;
+    timer_t tid;
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    se.sigev_notify = SIGEV_SIGNAL;
+    se.sigev_signo = ITIMER_SIGNAL;
+    se.sigev_value.sival_int = ITIMER_SIGNAL;
+    if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
+	barf("can't create virtual timer");
+    }
+    it.it_value.tv_sec = ms / 1000;
+    it.it_value.tv_nsec = 1000000 * (ms - 1000 * it.it_value.tv_sec);
+    it.it_interval = it.it_value;
+    return timer_settime(tid, TIMER_RELTIME, &it, NULL);
+}
+
+int
+stopTicker()
+{
+    struct sigevent se;
+    struct itimerspec it;
+    timer_t tid;
+
+#if !defined(THREADED_RTS)
+    timestamp = getourtimeofday();
+#endif
+
+    se.sigev_notify = SIGEV_SIGNAL;
+    se.sigev_signo = ITIMER_SIGNAL;
+    se.sigev_value.sival_int = ITIMER_SIGNAL;
+    if (timer_create(CLOCK_VIRTUAL, &se, &tid)) {
+	barf("can't create virtual timer");
+    }
+    it.it_value.tv_sec = 0;
+    it.it_value.tv_nsec = 0;
+    it.it_interval = it.it_value;
+    return timer_settime(tid, TIMER_RELTIME, &it, NULL);
+}
+# endif
+
+#if 0
+/* Currently unused */
+void
+block_vtalrm_signal(void)
+{
+    sigset_t signals;
+    
+    sigemptyset(&signals);
+    sigaddset(&signals, ITIMER_SIGNAL);
+
+    (void) sigprocmask(SIG_BLOCK, &signals, NULL);
+}
+
+void
+unblock_vtalrm_signal(void)
+{
+    sigset_t signals;
+    
+    sigemptyset(&signals);
+    sigaddset(&signals, ITIMER_SIGNAL);
+
+    (void) sigprocmask(SIG_UNBLOCK, &signals, NULL);
+}
+#endif
+
+/* gettimeofday() takes around 1us on our 500MHz PIII.  Since we're
+ * only calling it 50 times/s, it shouldn't have any great impact.
+ */
+lnat
+getourtimeofday(void)
+{
+  struct timeval tv;
+  gettimeofday(&tv, (struct timezone *) NULL);
+  	// cast to lnat because nat may be 64 bit when int is only 32 bit
+  return ((lnat)tv.tv_sec * TICK_FREQUENCY +
+	  (lnat)tv.tv_usec * TICK_FREQUENCY / 1000000);
+}
diff --git a/rts/posix/Itimer.h b/rts/posix/Itimer.h
new file mode 100644
index 0000000000..09d01bde54
--- /dev/null
+++ b/rts/posix/Itimer.h
@@ -0,0 +1,19 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team 1998-2005
+ *
+ * Interval timer for profiling and pre-emptive scheduling.
+ *
+ * ---------------------------------------------------------------------------*/
+
+#ifndef ITIMER_H
+#define ITIMER_H
+
+extern lnat getourtimeofday   ( void );
+#if 0
+/* unused */
+extern void block_vtalrm_signal       ( void );
+extern void unblock_vtalrm_signal     ( void );
+#endif
+
+#endif /* ITIMER_H */
diff --git a/rts/posix/OSThreads.c b/rts/posix/OSThreads.c
new file mode 100644
index 0000000000..07bd762130
--- /dev/null
+++ b/rts/posix/OSThreads.c
@@ -0,0 +1,166 @@
+/* ---------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 2001-2005
+ *
+ * Accessing OS threads functionality in a (mostly) OS-independent
+ * manner. 
+ *
+ * --------------------------------------------------------------------------*/
+
+#if defined(DEBUG) && defined(__linux__)
+/* We want GNU extensions in DEBUG mode for mutex error checking */
+#define _GNU_SOURCE
+#endif
+
+#include "Rts.h"
+#if defined(THREADED_RTS)
+#include "OSThreads.h"
+#include "RtsUtils.h"
+
+#if HAVE_STRING_H
+#include <string.h>
+#endif
+
+#if !defined(HAVE_PTHREAD_H)
+#error pthreads.h is required for the threaded RTS on Posix platforms
+#endif
+
+/*
+ * This (allegedly) OS threads independent layer was initially
+ * abstracted away from code that used Pthreads, so the functions
+ * provided here are mostly just wrappers to the Pthreads API.
+ *
+ */
+
+void
+initCondition( Condition* pCond )
+{
+  pthread_cond_init(pCond, NULL);
+  return;
+}
+
+void
+closeCondition( Condition* pCond )
+{
+  pthread_cond_destroy(pCond);
+  return;
+}
+
+rtsBool
+broadcastCondition ( Condition* pCond )
+{
+  return (pthread_cond_broadcast(pCond) == 0);
+}
+
+rtsBool
+signalCondition ( Condition* pCond )
+{
+  return (pthread_cond_signal(pCond) == 0);
+}
+
+rtsBool
+waitCondition ( Condition* pCond, Mutex* pMut )
+{
+  return (pthread_cond_wait(pCond,pMut) == 0);
+}
+
+void
+yieldThread()
+{
+  sched_yield();
+  return;
+}
+
+void
+shutdownThread()
+{
+  pthread_exit(NULL);
+}
+
+int
+createOSThread (OSThreadId* pId, OSThreadProc *startProc, void *param)
+{
+  int result = pthread_create(pId, NULL, (void *(*)(void *))startProc, param);
+  if(!result)
+    pthread_detach(*pId);
+  return result;
+}
+
+OSThreadId
+osThreadId()
+{
+  return pthread_self();
+}
+
+void
+initMutex(Mutex* pMut)
+{
+#if defined(DEBUG) && defined(linux_HOST_OS)
+    pthread_mutexattr_t attr;
+    pthread_mutexattr_init(&attr);
+    pthread_mutexattr_settype(&attr,PTHREAD_MUTEX_ERRORCHECK_NP);
+    pthread_mutex_init(pMut,&attr);
+#else
+    pthread_mutex_init(pMut,NULL);
+#endif
+    return;
+}
+
+void
+newThreadLocalKey (ThreadLocalKey *key)
+{
+    int r;
+    if ((r = pthread_key_create(key, NULL)) != 0) {
+	barf("newThreadLocalKey: %s", strerror(r));
+    }
+}
+
+void *
+getThreadLocalVar (ThreadLocalKey *key)
+{
+    return pthread_getspecific(*key);
+    // Note: a return value of NULL can indicate that either the key
+    // is not valid, or the key is valid and the data value has not
+    // yet been set.  We need to use the latter case, so we cannot
+    // detect errors here.
+}
+
+void
+setThreadLocalVar (ThreadLocalKey *key, void *value)
+{
+    int r;
+    if ((r = pthread_setspecific(*key,value)) != 0) {
+	barf("setThreadLocalVar: %s", strerror(r));
+    }
+}
+
+static void *
+forkOS_createThreadWrapper ( void * entry )
+{
+    Capability *cap;
+    cap = rts_lock();
+    cap = rts_evalStableIO(cap, (HsStablePtr) entry, NULL);
+    rts_unlock(cap);
+    return NULL;
+}
+
+int
+forkOS_createThread ( HsStablePtr entry )
+{
+    pthread_t tid;
+    int result = pthread_create(&tid, NULL,
+				forkOS_createThreadWrapper, (void*)entry);
+    if(!result)
+        pthread_detach(tid);
+    return result;
+}
+
+#else /* !defined(THREADED_RTS) */
+
+int
+forkOS_createThread ( HsStablePtr entry STG_UNUSED )
+{
+    return -1;
+}
+
+#endif /* !defined(THREADED_RTS) */
diff --git a/rts/posix/Select.c b/rts/posix/Select.c
new file mode 100644
index 0000000000..e21ced03ab
--- /dev/null
+++ b/rts/posix/Select.c
@@ -0,0 +1,279 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team 1995-2002
+ *
+ * Support for concurrent non-blocking I/O and thread waiting.
+ *
+ * ---------------------------------------------------------------------------*/
+
+/* we're outside the realms of POSIX here... */
+/* #include "PosixSource.h" */
+
+#include "Rts.h"
+#include "Schedule.h"
+#include "RtsUtils.h"
+#include "RtsFlags.h"
+#include "Timer.h"
+#include "Itimer.h"
+#include "Signals.h"
+#include "Capability.h"
+#include "posix/Select.h"
+
+# ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+# endif
+
+# ifdef HAVE_SYS_TIME_H
+#  include <sys/time.h>
+# endif
+
+#include <errno.h>
+#include <string.h>
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#if !defined(THREADED_RTS)
+/* last timestamp */
+lnat timestamp = 0;
+
+/* 
+ * The threaded RTS uses an IO-manager thread in Haskell instead (see GHC.Conc) 
+ */
+
+/* There's a clever trick here to avoid problems when the time wraps
+ * around.  Since our maximum delay is smaller than 31 bits of ticks
+ * (it's actually 31 bits of microseconds), we can safely check
+ * whether a timer has expired even if our timer will wrap around
+ * before the target is reached, using the following formula:
+ *
+ *        (int)((uint)current_time - (uint)target_time) < 0
+ *
+ * if this is true, then our time has expired.
+ * (idea due to Andy Gill).
+ */
+static rtsBool
+wakeUpSleepingThreads(lnat ticks)
+{
+    StgTSO *tso;
+    rtsBool flag = rtsFalse;
+
+    while (sleeping_queue != END_TSO_QUEUE &&
+	   (int)(ticks - sleeping_queue->block_info.target) > 0) {
+	tso = sleeping_queue;
+	sleeping_queue = tso->link;
+	tso->why_blocked = NotBlocked;
+	tso->link = END_TSO_QUEUE;
+	IF_DEBUG(scheduler,debugBelch("Waking up sleeping thread %d\n", tso->id));
+	// MainCapability: this code is !THREADED_RTS
+	pushOnRunQueue(&MainCapability,tso);
+	flag = rtsTrue;
+    }
+    return flag;
+}
+
+/* Argument 'wait' says whether to wait for I/O to become available,
+ * or whether to just check and return immediately.  If there are
+ * other threads ready to run, we normally do the non-waiting variety,
+ * otherwise we wait (see Schedule.c).
+ *
+ * SMP note: must be called with sched_mutex locked.
+ *
+ * Windows: select only works on sockets, so this doesn't really work,
+ * though it makes things better than before. MsgWaitForMultipleObjects
+ * should really be used, though it only seems to work for read handles,
+ * not write handles.
+ *
+ */
+void
+awaitEvent(rtsBool wait)
+{
+    StgTSO *tso, *prev, *next;
+    rtsBool ready;
+    fd_set rfd,wfd;
+    int numFound;
+    int maxfd = -1;
+    rtsBool select_succeeded = rtsTrue;
+    rtsBool unblock_all = rtsFalse;
+    struct timeval tv;
+    lnat min, ticks;
+
+    tv.tv_sec  = 0;
+    tv.tv_usec = 0;
+    
+    IF_DEBUG(scheduler,
+	     debugBelch("scheduler: checking for threads blocked on I/O");
+	     if (wait) {
+		 debugBelch(" (waiting)");
+	     }
+	     debugBelch("\n");
+	     );
+
+    /* loop until we've woken up some threads.  This loop is needed
+     * because the select timing isn't accurate, we sometimes sleep
+     * for a while but not long enough to wake up a thread in
+     * a threadDelay.
+     */
+    do {
+
+      ticks = timestamp = getourtimeofday();
+      if (wakeUpSleepingThreads(ticks)) { 
+	  return;
+      }
+
+      if (!wait) {
+	  min = 0;
+      } else if (sleeping_queue != END_TSO_QUEUE) {
+	  min = (sleeping_queue->block_info.target - ticks) 
+	      * TICK_MILLISECS * 1000;
+      } else {
+	  min = 0x7ffffff;
+      }
+
+      /* 
+       * Collect all of the fd's that we're interested in
+       */
+      FD_ZERO(&rfd);
+      FD_ZERO(&wfd);
+
+      for(tso = blocked_queue_hd; tso != END_TSO_QUEUE; tso = next) {
+	next = tso->link;
+
+	switch (tso->why_blocked) {
+	case BlockedOnRead:
+	  { 
+	    int fd = tso->block_info.fd;
+	    if (fd >= FD_SETSIZE) {
+		barf("awaitEvent: descriptor out of range");
+	    }
+	    maxfd = (fd > maxfd) ? fd : maxfd;
+	    FD_SET(fd, &rfd);
+	    continue;
+	  }
+
+	case BlockedOnWrite:
+	  { 
+	    int fd = tso->block_info.fd;
+	    if (fd >= FD_SETSIZE) {
+		barf("awaitEvent: descriptor out of range");
+	    }
+	    maxfd = (fd > maxfd) ? fd : maxfd;
+	    FD_SET(fd, &wfd);
+	    continue;
+	  }
+
+	default:
+	  barf("AwaitEvent");
+	}
+      }
+
+      /* Check for any interesting events */
+      
+      tv.tv_sec  = min / 1000000;
+      tv.tv_usec = min % 1000000;
+
+      while ((numFound = select(maxfd+1, &rfd, &wfd, NULL, &tv)) < 0) {
+	  if (errno != EINTR) {
+	    /* Handle bad file descriptors by unblocking all the
+	       waiting threads. Why? Because a thread might have been
+	       a bit naughty and closed a file descriptor while another
+	       was blocked waiting. This is less-than-good programming
+	       practice, but having the RTS as a result fall over isn't
+	       acceptable, so we simply unblock all the waiting threads
+	       should we see a bad file descriptor & give the threads
+	       a chance to clean up their act. 
+	       
+	       Note: assume here that threads becoming unblocked
+	       will try to read/write the file descriptor before trying
+	       to issue a threadWaitRead/threadWaitWrite again (==> an
+	       IOError will result for the thread that's got the bad
+	       file descriptor.) Hence, there's no danger of a bad
+	       file descriptor being repeatedly select()'ed on, so
+	       the RTS won't loop.
+	    */
+	    if ( errno == EBADF ) {
+	      unblock_all = rtsTrue;
+	      break;
+	    } else {
+ 	      perror("select");
+	      barf("select failed");
+	    }
+	  }
+
+	  /* We got a signal; could be one of ours.  If so, we need
+	   * to start up the signal handler straight away, otherwise
+	   * we could block for a long time before the signal is
+	   * serviced.
+	   */
+#if defined(RTS_USER_SIGNALS)
+	  if (signals_pending()) {
+	      startSignalHandlers(&MainCapability);
+	      return; /* still hold the lock */
+	  }
+#endif
+
+	  /* we were interrupted, return to the scheduler immediately.
+	   */
+	  if (sched_state >= SCHED_INTERRUPTING) {
+	      return; /* still hold the lock */
+	  }
+	  
+	  /* check for threads that need waking up 
+	   */
+	  wakeUpSleepingThreads(getourtimeofday());
+	  
+	  /* If new runnable threads have arrived, stop waiting for
+	   * I/O and run them.
+	   */
+	  if (!emptyRunQueue(&MainCapability)) {
+	      return; /* still hold the lock */
+	  }
+      }
+
+      /* Step through the waiting queue, unblocking every thread that now has
+       * a file descriptor in a ready state.
+       */
+
+      prev = NULL;
+      if (select_succeeded || unblock_all) {
+	  for(tso = blocked_queue_hd; tso != END_TSO_QUEUE; tso = next) {
+	      next = tso->link;
+	      switch (tso->why_blocked) {
+	      case BlockedOnRead:
+		  ready = unblock_all || FD_ISSET(tso->block_info.fd, &rfd);
+		  break;
+	      case BlockedOnWrite:
+		  ready = unblock_all || FD_ISSET(tso->block_info.fd, &wfd);
+		  break;
+	      default:
+		  barf("awaitEvent");
+	      }
+      
+	      if (ready) {
+		  IF_DEBUG(scheduler,debugBelch("Waking up blocked thread %d\n", tso->id));
+		  tso->why_blocked = NotBlocked;
+		  tso->link = END_TSO_QUEUE;
+		  pushOnRunQueue(&MainCapability,tso);
+	      } else {
+		  if (prev == NULL)
+		      blocked_queue_hd = tso;
+		  else
+		      prev->link = tso;
+		  prev = tso;
+	      }
+	  }
+
+	  if (prev == NULL)
+	      blocked_queue_hd = blocked_queue_tl = END_TSO_QUEUE;
+	  else {
+	      prev->link = END_TSO_QUEUE;
+	      blocked_queue_tl = prev;
+	  }
+      }
+      
+    } while (wait && sched_state == SCHED_RUNNING
+	     && emptyRunQueue(&MainCapability));
+}
+
+#endif /* THREADED_RTS */
diff --git a/rts/posix/Select.h b/rts/posix/Select.h
new file mode 100644
index 0000000000..8825562974
--- /dev/null
+++ b/rts/posix/Select.h
@@ -0,0 +1,26 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team 1998-2005
+ *
+ * Prototypes for functions in Select.c
+ *
+ * -------------------------------------------------------------------------*/
+
+#ifndef SELECT_H
+#define SELECT_H
+
+#if !defined(THREADED_RTS)
+/* In Select.c */
+extern lnat RTS_VAR(timestamp);
+
+/* awaitEvent(rtsBool wait)
+ *
+ * Checks for blocked threads that need to be woken.
+ *
+ * Called from STG :  NO
+ * Locks assumed   :  sched_mutex
+ */
+void awaitEvent(rtsBool wait);  /* In Select.c */
+#endif
+
+#endif /* SELECT_H */
diff --git a/rts/posix/Signals.c b/rts/posix/Signals.c
new file mode 100644
index 0000000000..5f5f77fd39
--- /dev/null
+++ b/rts/posix/Signals.c
@@ -0,0 +1,510 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1998-2005
+ *
+ * Signal processing / handling.
+ *
+ * ---------------------------------------------------------------------------*/
+
+/* This is non-Posix-compliant.
+   #include "PosixSource.h" 
+*/
+#include "Rts.h"
+#include "SchedAPI.h"
+#include "Schedule.h"
+#include "RtsSignals.h"
+#include "posix/Signals.h"
+#include "RtsUtils.h"
+#include "RtsFlags.h"
+
+#ifdef alpha_HOST_ARCH
+# if defined(linux_HOST_OS)
+#  include <asm/fpu.h>
+# else
+#  include <machine/fpu.h>
+# endif
+#endif
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifdef HAVE_SIGNAL_H
+# include <signal.h>
+#endif
+
+#include <stdlib.h>
+
+/* This curious flag is provided for the benefit of the Haskell binding
+ * to POSIX.1 to control whether or not to include SA_NOCLDSTOP when
+ * installing a SIGCHLD handler. 
+ */
+StgInt nocldstop = 0;
+
+/* -----------------------------------------------------------------------------
+ * The table of signal handlers
+ * -------------------------------------------------------------------------- */
+
+#if defined(RTS_USER_SIGNALS)
+
+/* SUP: The type of handlers is a little bit, well, doubtful... */
+StgInt *signal_handlers = NULL; /* Dynamically grown array of signal handlers */
+static StgInt nHandlers = 0;    /* Size of handlers array */
+
+static nat n_haskell_handlers = 0;
+
+/* -----------------------------------------------------------------------------
+ * Allocate/resize the table of signal handlers.
+ * -------------------------------------------------------------------------- */
+
+static void
+more_handlers(I_ sig)
+{
+    StgInt i;
+
+    if (sig < nHandlers)
+	return;
+
+    if (signal_handlers == NULL)
+	signal_handlers = (StgInt *)stgMallocBytes((sig + 1) * sizeof(StgInt), "more_handlers");
+    else
+	signal_handlers = (StgInt *)stgReallocBytes(signal_handlers, (sig + 1) * sizeof(StgInt), "more_handlers");
+
+    for(i = nHandlers; i <= sig; i++)
+	// Fill in the new slots with default actions
+	signal_handlers[i] = STG_SIG_DFL;
+
+    nHandlers = sig + 1;
+}
+
+/* -----------------------------------------------------------------------------
+ * Pending Handlers
+ *
+ * The mechanism for starting handlers differs between the threaded
+ * (THREADED_RTS) and non-threaded versions of the RTS.
+ *
+ * When the RTS is single-threaded, we just write the pending signal
+ * handlers into a buffer, and start a thread for each one in the
+ * scheduler loop.
+ *
+ * When THREADED_RTS, the problem is that signals might be
+ * delivered to multiple threads, so we would need to synchronise
+ * access to pending_handler_buf somehow.  Using thread
+ * synchronisation from a signal handler isn't possible in general
+ * (some OSs support it, eg. MacOS X, but not all).  So instead:
+ *
+ *   - the signal handler writes the signal number into the pipe
+ *     managed by the IO manager thread (see GHC.Conc).
+ *   - the IO manager picks up the signal number and calls
+ *     startSignalHandler() to start the thread.
+ *
+ * This also has the nice property that we don't need to arrange to
+ * wake up a worker task to start the signal handler: the IO manager
+ * wakes up when we write into the pipe.
+ *
+ * -------------------------------------------------------------------------- */
+
+// Here's the pipe into which we will send our signals
+static int io_manager_pipe = -1;
+
+void
+setIOManagerPipe (int fd)
+{
+    // only called when THREADED_RTS, but unconditionally
+    // compiled here because GHC.Conc depends on it.
+    io_manager_pipe = fd;
+}
+
+#if !defined(THREADED_RTS)
+
+#define N_PENDING_HANDLERS 16
+
+StgPtr pending_handler_buf[N_PENDING_HANDLERS];
+StgPtr *next_pending_handler = pending_handler_buf;
+
+#endif /* THREADED_RTS */
+
+/* -----------------------------------------------------------------------------
+ * SIGCONT handler
+ *
+ * It seems that shells tend to put stdin back into blocking mode
+ * following a suspend/resume of the process.  Here we arrange to put
+ * it back into non-blocking mode.  We don't do anything to
+ * stdout/stderr because these handles don't get put into non-blocking
+ * mode at all - see the comments on stdout/stderr in PrelHandle.hsc.
+ * -------------------------------------------------------------------------- */
+
+static void
+cont_handler(int sig STG_UNUSED)
+{
+    setNonBlockingFd(0);
+}
+
+/* -----------------------------------------------------------------------------
+ * Low-level signal handler
+ *
+ * Places the requested handler on a stack of pending handlers to be
+ * started up at the next context switch.
+ * -------------------------------------------------------------------------- */
+
+static void
+generic_handler(int sig)
+{
+    sigset_t signals;
+
+#if defined(THREADED_RTS)
+
+    if (io_manager_pipe != -1)
+    {
+	// Write the signal number into the pipe as a single byte.  We
+	// hope that signals fit into a byte...
+	StgWord8 csig = (StgWord8)sig;
+	write(io_manager_pipe, &csig, 1);
+    }
+    // If the IO manager hasn't told us what the FD of the write end
+    // of its pipe is, there's not much we can do here, so just ignore
+    // the signal..
+
+#else /* not THREADED_RTS */
+
+    /* Can't call allocate from here.  Probably can't call malloc
+       either.  However, we have to schedule a new thread somehow.
+
+       It's probably ok to request a context switch and allow the
+       scheduler to  start the handler thread, but how do we
+       communicate this to the scheduler?
+
+       We need some kind of locking, but with low overhead (i.e. no
+       blocking signals every time around the scheduler).
+       
+       Signal Handlers are atomic (i.e. they can't be interrupted), and
+       we can make use of this.  We just need to make sure the
+       critical section of the scheduler can't be interrupted - the
+       only way to do this is to block signals.  However, we can lower
+       the overhead by only blocking signals when there are any
+       handlers to run, i.e. the set of pending handlers is
+       non-empty.
+    */
+       
+    /* We use a stack to store the pending signals.  We can't
+       dynamically grow this since we can't allocate any memory from
+       within a signal handler.
+
+       Hence unfortunately we have to bomb out if the buffer
+       overflows.  It might be acceptable to carry on in certain
+       circumstances, depending on the signal.  
+    */
+
+    *next_pending_handler++ = deRefStablePtr((StgStablePtr)signal_handlers[sig]);
+
+    // stack full?
+    if (next_pending_handler == &pending_handler_buf[N_PENDING_HANDLERS]) {
+	errorBelch("too many pending signals");
+	stg_exit(EXIT_FAILURE);
+    }
+    
+#endif /* THREADED_RTS */
+
+    // re-establish the signal handler, and carry on
+    sigemptyset(&signals);
+    sigaddset(&signals, sig);
+    sigprocmask(SIG_UNBLOCK, &signals, NULL);
+
+    // *always* do the SIGCONT handler, even if the user overrides it.
+    if (sig == SIGCONT) {
+	cont_handler(sig);
+    }
+
+    context_switch = 1;
+}
+
+/* -----------------------------------------------------------------------------
+ * Blocking/Unblocking of the user signals
+ * -------------------------------------------------------------------------- */
+
+static sigset_t userSignals;
+static sigset_t savedSignals;
+
+void
+initUserSignals(void)
+{
+    sigemptyset(&userSignals);
+}
+
+void
+blockUserSignals(void)
+{
+    sigprocmask(SIG_BLOCK, &userSignals, &savedSignals);
+}
+
+void
+unblockUserSignals(void)
+{
+    sigprocmask(SIG_SETMASK, &savedSignals, NULL);
+}
+
+rtsBool
+anyUserHandlers(void)
+{
+    return n_haskell_handlers != 0;
+}
+
+#if !defined(THREADED_RTS)
+void
+awaitUserSignals(void)
+{
+    while (!signals_pending() && sched_state == SCHED_RUNNING) {
+	pause();
+    }
+}
+#endif
+
+/* -----------------------------------------------------------------------------
+ * Install a Haskell signal handler.
+ * -------------------------------------------------------------------------- */
+
+int
+stg_sig_install(int sig, int spi, StgStablePtr *handler, void *mask)
+{
+    sigset_t signals, osignals;
+    struct sigaction action;
+    StgInt previous_spi;
+
+    // Block the signal until we figure out what to do
+    // Count on this to fail if the signal number is invalid
+    if (sig < 0 || sigemptyset(&signals) ||
+	sigaddset(&signals, sig) || sigprocmask(SIG_BLOCK, &signals, &osignals)) {
+	return STG_SIG_ERR;
+    }
+    
+    more_handlers(sig);
+
+    previous_spi = signal_handlers[sig];
+
+    action.sa_flags = 0;
+    
+    switch(spi) {
+    case STG_SIG_IGN:
+    	signal_handlers[sig] = STG_SIG_IGN;
+	sigdelset(&userSignals, sig);
+        action.sa_handler = SIG_IGN;
+    	break;
+    	
+    case STG_SIG_DFL:
+    	signal_handlers[sig] = STG_SIG_DFL;
+	sigdelset(&userSignals, sig);
+        action.sa_handler = SIG_DFL;
+    	break;
+
+    case STG_SIG_HAN:
+    case STG_SIG_RST:
+    	signal_handlers[sig] = (StgInt)*handler;
+	sigaddset(&userSignals, sig);
+    	action.sa_handler = generic_handler;
+	if (spi == STG_SIG_RST) {
+	    action.sa_flags = SA_RESETHAND;
+	}
+	n_haskell_handlers++;
+    	break;
+
+    default:
+        barf("stg_sig_install: bad spi");
+    }
+
+    if (mask != NULL)
+        action.sa_mask = *(sigset_t *)mask;
+    else
+	sigemptyset(&action.sa_mask);
+
+    action.sa_flags |= sig == SIGCHLD && nocldstop ? SA_NOCLDSTOP : 0;
+
+    if (sigaction(sig, &action, NULL) || 
+	sigprocmask(SIG_SETMASK, &osignals, NULL)) 
+    {
+	// need to return an error code, so avoid a stable pointer leak
+	// by freeing the previous handler if there was one.
+	if (previous_spi >= 0) {
+	    freeStablePtr(stgCast(StgStablePtr,signal_handlers[sig]));
+	    n_haskell_handlers--;
+	}
+	return STG_SIG_ERR;
+    }
+
+    if (previous_spi == STG_SIG_DFL || previous_spi == STG_SIG_IGN
+	|| previous_spi == STG_SIG_ERR) {
+	return previous_spi;
+    } else {
+	*handler = (StgStablePtr)previous_spi;
+	return STG_SIG_HAN;
+    }
+}
+
+/* -----------------------------------------------------------------------------
+ * Creating new threads for signal handlers.
+ * -------------------------------------------------------------------------- */
+
+#if !defined(THREADED_RTS)
+void
+startSignalHandlers(Capability *cap)
+{
+  blockUserSignals();
+  
+  while (next_pending_handler != pending_handler_buf) {
+
+    next_pending_handler--;
+
+    scheduleThread (cap,
+	createIOThread(cap,
+		       RtsFlags.GcFlags.initialStkSize, 
+		       (StgClosure *) *next_pending_handler));
+  }
+
+  unblockUserSignals();
+}
+#endif
+
+/* ----------------------------------------------------------------------------
+ * Mark signal handlers during GC.
+ *
+ * We do this rather than trying to start all the signal handlers
+ * prior to GC, because that requires extra heap for the new threads.
+ * Signals must be blocked (see blockUserSignals() above) during GC to
+ * avoid race conditions.
+ * -------------------------------------------------------------------------- */
+
+#if !defined(THREADED_RTS)
+void
+markSignalHandlers (evac_fn evac)
+{
+    StgPtr *p;
+
+    p = next_pending_handler;
+    while (p != pending_handler_buf) {
+	p--;
+	evac((StgClosure **)p);
+    }
+}
+#else
+void
+markSignalHandlers (evac_fn evac STG_UNUSED)
+{
+}
+#endif
+
+#else /* !RTS_USER_SIGNALS */
+StgInt 
+stg_sig_install(StgInt sig STG_UNUSED,
+		StgInt spi STG_UNUSED,
+		StgStablePtr* handler STG_UNUSED,
+		void* mask STG_UNUSED)
+{
+  //barf("User signals not supported");
+  return STG_SIG_DFL;
+}
+
+#endif
+
+#if defined(RTS_USER_SIGNALS)
+/* -----------------------------------------------------------------------------
+ * SIGINT handler.
+ *
+ * We like to shutdown nicely after receiving a SIGINT, write out the
+ * stats, write profiling info, close open files and flush buffers etc.
+ * -------------------------------------------------------------------------- */
+#ifdef SMP
+pthread_t startup_guy;
+#endif
+
+static void
+shutdown_handler(int sig STG_UNUSED)
+{
+#ifdef SMP
+    // if I'm a worker thread, send this signal to the guy who
+    // originally called startupHaskell().  Since we're handling
+    // the signal, it won't be a "send to all threads" type of signal
+    // (according to the POSIX threads spec).
+    if (pthread_self() != startup_guy) {
+	pthread_kill(startup_guy, sig);
+	return;
+    }
+#endif
+
+    // If we're already trying to interrupt the RTS, terminate with
+    // extreme prejudice.  So the first ^C tries to exit the program
+    // cleanly, and the second one just kills it.
+    if (sched_state >= SCHED_INTERRUPTING) {
+	stg_exit(EXIT_INTERRUPTED);
+    } else {
+	interruptStgRts();
+    }
+}
+
+/* -----------------------------------------------------------------------------
+ * Install default signal handlers.
+ *
+ * The RTS installs a default signal handler for catching
+ * SIGINT, so that we can perform an orderly shutdown.
+ *
+ * Haskell code may install their own SIGINT handler, which is
+ * fine, provided they're so kind as to put back the old one
+ * when they de-install.
+ *
+ * In addition to handling SIGINT, the RTS also handles SIGFPE
+ * by ignoring it.  Apparently IEEE requires floating-point
+ * exceptions to be ignored by default, but alpha-dec-osf3
+ * doesn't seem to do so.
+ * -------------------------------------------------------------------------- */
+void
+initDefaultHandlers()
+{
+    struct sigaction action,oact;
+
+#ifdef SMP
+    startup_guy = pthread_self();
+#endif
+
+    // install the SIGINT handler
+    action.sa_handler = shutdown_handler;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGINT, &action, &oact) != 0) {
+	errorBelch("warning: failed to install SIGINT handler");
+    }
+
+#if defined(HAVE_SIGINTERRUPT)
+    siginterrupt(SIGINT, 1);	// isn't this the default? --SDM
+#endif
+
+    // install the SIGCONT handler
+    action.sa_handler = cont_handler;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGCONT, &action, &oact) != 0) {
+	errorBelch("warning: failed to install SIGCONT handler");
+    }
+
+    // install the SIGFPE handler
+
+    // In addition to handling SIGINT, also handle SIGFPE by ignoring it.
+    // Apparently IEEE requires floating-point exceptions to be ignored by
+    // default, but alpha-dec-osf3 doesn't seem to do so.
+
+    // Commented out by SDM 2/7/2002: this causes an infinite loop on
+    // some architectures when an integer division by zero occurs: we
+    // don't recover from the floating point exception, and the
+    // program just generates another one immediately.
+#if 0
+    action.sa_handler = SIG_IGN;
+    sigemptyset(&action.sa_mask);
+    action.sa_flags = 0;
+    if (sigaction(SIGFPE, &action, &oact) != 0) {
+	errorBelch("warning: failed to install SIGFPE handler");
+    }
+#endif
+
+#ifdef alpha_HOST_ARCH
+    ieee_set_fp_control(0);
+#endif
+}
+
+#endif /* RTS_USER_SIGNALS */
diff --git a/rts/posix/Signals.h b/rts/posix/Signals.h
new file mode 100644
index 0000000000..39477f8c6a
--- /dev/null
+++ b/rts/posix/Signals.h
@@ -0,0 +1,26 @@
+/* -----------------------------------------------------------------------------
+ *
+ * (c) The GHC Team, 1998-2005
+ *
+ * Signal processing / handling.
+ *
+ * ---------------------------------------------------------------------------*/
+
+#ifndef POSIX_SIGNALS_H
+#define POSIX_SIGNALS_H
+
+extern rtsBool anyUserHandlers(void);
+
+#if !defined(THREADED_RTS)
+
+extern StgPtr pending_handler_buf[];
+extern StgPtr *next_pending_handler;
+#define signals_pending() (next_pending_handler != pending_handler_buf)
+void startSignalHandlers(Capability *cap);
+
+#endif
+
+extern StgInt *signal_handlers;
+
+#endif /* POSIX_SIGNALS_H */
+