From Nicholas Duffek (with minor changes by Martin Hunt,

	Louis Hamilton, and Kevin Buettner):
	* aix-thread.c: New file.

2 files changed, 1498 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5f6a4fd..861f270 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2002-07-12  Kevin Buettner  <kevinb@redhat.com>
+
+	From Nicholas Duffek (with minor changes by Martin Hunt, 
+	Louis Hamilton, and Kevin Buettner):
+	* aix-thread.c: New file.
+
 2002-07-12  Petr Sorfa <petrs@caldera.com>
 
         *  dwarf2read.c (dwarf2_invalid_attrib_class): New
diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
new file mode 100644
index 0000000..7ca8e82
--- /dev/null
+++ b/gdb/aix-thread.c
@@ -0,0 +1,1492 @@
+/* Low level interface for debugging AIX 4.3+ pthreads.
+
+   Copyright 1999, 2000, 2002 Free Software Foundation, Inc.
+   Written by Nick Duffek <nsd@redhat.com>.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+
+/* This module uses the libpthdebug.a library provided by AIX 4.3+ for
+   debugging pthread applications.
+
+   Some name prefix conventions:
+     pthdb_	provided by libpthdebug.a
+     pdc_	callbacks that this module provides to libpthdebug.a
+     pd_	variables or functions interfacing with libpthdebug.a
+
+   libpthdebug peculiarities:
+
+     - pthdb_ptid_pthread() is prototyped in <sys/pthdebug.h>, but it's not
+       documented, and after several calls it stops working and causes other
+       libpthdebug functions to fail.
+
+     - pthdb_tid_pthread() doesn't always work after pthdb_session_update(),
+       but it does work after cycling through all threads using
+       pthdb_pthread().
+
+     */
+
+#include "defs.h"
+#include "gdbthread.h"
+#include "target.h"
+#include "inferior.h"
+#include "regcache.h"
+
+#if 0
+#include "coff/internal.h"	/* for libcoff.h */
+#include "bfd/libcoff.h"	/* for xcoff_data */
+#endif
+
+#include <procinfo.h>
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/reg.h>
+#if 0
+#include <pthread.h>
+#endif
+#include <sched.h>
+#include <sys/pthdebug.h>
+
+/* Whether to emit debugging output. */
+
+#define DEBUG 0
+
+/* Default debugging output file, overridden by envvar UWTHR_DEBUG. */
+
+#define DEBUG_FILE "/dev/tty"
+
+/* #if DEBUG, write string S to the debugging output channel. */
+
+#if !DEBUG
+# define DBG(fmt_and_args)
+# define DBG2(fmt_and_args)
+#else
+# define DBG(fmt_and_args) dbg fmt_and_args
+# define DBG2(fmt_and_args) dbg fmt_and_args
+#endif
+
+/* in AIX 5.1, functions use pthdb_tid_t instead of tid_t */
+#ifndef PTHDB_VERSION_3
+#define pthdb_tid_t	tid_t
+#endif
+
+/* Return whether to treat PID as a debuggable thread id. */
+
+#define PD_TID(ptid)	(pd_active && ptid_get_tid (ptid) != 0)
+
+/* Build a thread ptid.  */
+#define BUILD_THREAD(TID, PID) ptid_build (PID, 0, TID)
+
+/* Build and lwp ptid.  */
+#define BUILD_LWP(LWP, PID) MERGEPID (PID, LWP)
+
+/* Call error() with a message indicating that libpthdebug FUNC failed with
+   STATUS. */
+
+#define PD_ERROR(func, status) \
+  error ("aix-thread: %s returned %s", func, pd_status2str (status))
+
+/* pthdb_user_t value that we pass to pthdb functions.  0 causes
+   PTHDB_BAD_USER errors, so use 1. */
+
+#define PD_USER	1
+
+/* Success and failure values returned by pthdb callbacks. */
+
+#define PDC_SUCCESS	PTHDB_SUCCESS
+#define PDC_FAILURE	PTHDB_CALLBACK
+
+/* Convert composite process/thread inferior_ptid to a process id, evaluate
+   base_ops function CALL, and then restore inferior_ptid. */
+
+#define CALL_BASE(call)					\
+  do {							\
+    struct cleanup *cleanup = save_inferior_ptid ();	\
+    inferior_ptid = pid_to_ptid (PIDGET (inferior_ptid)); \
+    call;						\
+    do_cleanups (cleanup);				\
+  } while (0)
+
+/* Private data attached to each element in GDB's thread list. */
+
+struct private_thread_info {
+  pthdb_pthread_t pdtid;	/* thread's libpthdebug id */
+  pthdb_tid_t tid;			/* kernel thread id */
+};
+
+/* Information about a thread of which libpthdebug is aware. */
+
+struct pd_thread {
+  pthdb_pthread_t pdtid;
+  pthread_t pthid;
+  pthdb_tid_t tid;
+};
+
+/* This module's target-specific operations, active while pd_able is true. */
+
+static struct target_ops ops;
+
+/* Copy of the target over which ops is pushed.  This is
+   more convenient than a pointer to child_ops or core_ops, because
+   they lack current_target's default callbacks. */
+
+static struct target_ops base_ops;
+
+/* Address of the function that libpthread will call when libpthdebug is
+   ready to be initialized. */
+
+static CORE_ADDR pd_brk_addr;
+
+/* Whether the current application is debuggable by pthdb. */
+
+static int pd_able = 0;
+
+/* Whether a threaded application is being debugged. */
+
+static int pd_active = 0;
+
+/* Whether the current architecture is 64-bit.  Only valid when pd_able is
+   true. */
+
+static int arch64;
+
+/* Saved pointer to previous owner of target_new_objfile_hook. */
+
+static void (*target_new_objfile_chain)(struct objfile *);
+
+/* Forward declarations for pthdb callbacks. */
+
+static int pdc_symbol_addrs (pthdb_user_t, pthdb_symbol_t *, int);
+static int pdc_read_data (pthdb_user_t, void *, pthdb_addr_t, size_t);
+static int pdc_write_data (pthdb_user_t, void *, pthdb_addr_t, size_t);
+static int pdc_read_regs (pthdb_user_t user, pthdb_tid_t tid,
+			  unsigned long long flags, pthdb_context_t *context);
+static int pdc_write_regs (pthdb_user_t user, pthdb_tid_t tid,
+			   unsigned long long flags, pthdb_context_t *context);
+static int pdc_alloc (pthdb_user_t, size_t, void **);
+static int pdc_realloc (pthdb_user_t, void *, size_t, void **);
+static int pdc_dealloc (pthdb_user_t, void *);
+
+/* pthdb callbacks. */
+
+static pthdb_callbacks_t pd_callbacks = {
+  pdc_symbol_addrs,
+  pdc_read_data,
+  pdc_write_data,
+  pdc_read_regs,
+  pdc_write_regs,
+  pdc_alloc,
+  pdc_realloc,
+  pdc_dealloc,
+  NULL
+};
+
+/* Current pthdb session. */
+
+static pthdb_session_t pd_session;
+
+#if DEBUG
+/* DBG() helper: if printf-style FMT is non-null, format it with args and
+   display the result on the debugging output channel. */
+
+static void
+dbg (char *fmt, ...)
+{
+  static int fd = -1, len;
+  va_list args;
+  char buf[1024];
+  char *path;
+
+  if (!fmt)
+    return;
+
+  if (fd < 0)
+    {
+      path = getenv ("UWTHR_DEBUG");
+      if (!path)
+	path = DEBUG_FILE;
+      if ((fd = open (path, O_WRONLY | O_CREAT | O_TRUNC, 0664)) < 0)
+	error ("can't open %s\n", path);
+    }
+
+  va_start (args, fmt);
+  vsprintf (buf, fmt, args);
+  va_end (args);
+
+  len = strlen (buf);
+  buf[len] = '\n';
+  (void)write (fd, buf, len + 1);
+}
+#endif   /* DEBUG */
+
+/* Return a printable representation of pthdebug function return STATUS. */
+
+static char *
+pd_status2str (int status)
+{
+  switch (status)
+    {
+    case PTHDB_SUCCESS:		return "SUCCESS";
+    case PTHDB_NOSYS:		return "NOSYS";
+    case PTHDB_NOTSUP:		return "NOTSUP";
+    case PTHDB_BAD_VERSION:	return "BAD_VERSION";
+    case PTHDB_BAD_USER:	return "BAD_USER";
+    case PTHDB_BAD_SESSION:	return "BAD_SESSION";
+    case PTHDB_BAD_MODE:	return "BAD_MODE";
+    case PTHDB_BAD_FLAGS:	return "BAD_FLAGS";
+    case PTHDB_BAD_CALLBACK:	return "BAD_CALLBACK";
+    case PTHDB_BAD_POINTER:	return "BAD_POINTER";
+    case PTHDB_BAD_CMD:		return "BAD_CMD";
+    case PTHDB_BAD_PTHREAD:	return "BAD_PTHREAD";
+    case PTHDB_BAD_ATTR:	return "BAD_ATTR";
+    case PTHDB_BAD_MUTEX:	return "BAD_MUTEX";
+    case PTHDB_BAD_MUTEXATTR:	return "BAD_MUTEXATTR";
+    case PTHDB_BAD_COND:	return "BAD_COND";
+    case PTHDB_BAD_CONDATTR:	return "BAD_CONDATTR";
+    case PTHDB_BAD_RWLOCK:	return "BAD_RWLOCK";
+    case PTHDB_BAD_RWLOCKATTR:	return "BAD_RWLOCKATTR";
+    case PTHDB_BAD_KEY:		return "BAD_KEY";
+    case PTHDB_BAD_PTID:	return "BAD_PTID";
+    case PTHDB_BAD_TID:		return "BAD_TID";
+    case PTHDB_CALLBACK:	return "CALLBACK";
+    case PTHDB_CONTEXT:		return "CONTEXT";
+    case PTHDB_HELD:		return "HELD";
+    case PTHDB_NOT_HELD:	return "NOT_HELD";
+    case PTHDB_MEMORY:		return "MEMORY";
+    case PTHDB_NOT_PTHREADED:	return "NOT_PTHREADED";
+    case PTHDB_SYMBOL:		return "SYMBOL";
+    case PTHDB_NOT_AVAIL:	return "NOT_AVAIL";
+    case PTHDB_INTERNAL:	return "INTERNAL";
+    default:			return "UNKNOWN";
+    }
+}
+
+/* A call to ptrace(REQ, ID, ...) just returned RET.  Check for exceptional
+   conditions and either return nonlocally or else return 1 for success and 0
+   for failure. */
+
+static int
+ptrace_check (int req, int id, int ret)
+{
+  if (ret == 0 && !errno)
+    return 1;
+
+  /* According to ptrace(2), ptrace may fail with EPERM if "the Identifier
+     parameter corresponds to a kernel thread which is stopped in kernel mode
+     and whose computational state cannot be read or written."  This happens
+     quite often with register reads. */
+
+  switch (req)
+    {
+    case PTT_READ_GPRS:
+    case PTT_READ_FPRS:
+    case PTT_READ_SPRS:
+      if (ret == -1 && errno == EPERM)
+	goto strange;
+      break;
+    }
+  error ("aix-thread: ptrace (%d, %d) returned %d (errno = %d %s)",
+	 req, id, ret, errno, strerror (errno));
+
+ strange:
+  DBG2(("ptrace (%d, %d) = %d (errno = %d)", req, id, ret, errno));
+  return ret == -1 ? 0 : 1;
+}
+
+/* Call ptracex(REQ, ID, ADDR, DATA, BUF).  Return success. */
+
+static int
+ptrace64aix (int req, int id, long long addr, int data, int *buf)
+{
+  errno = 0;
+  return ptrace_check (req, id, ptracex (req, id, addr, data, buf));
+}
+
+/* Call ptrace(REQ, ID, ADDR, DATA, BUF).  Return success. */
+
+static int
+ptrace32 (int req, int id, int *addr, int data, int *buf)
+{
+  errno = 0;
+  return ptrace_check (req, id, ptrace (req, id, (int *)addr, data, buf));
+}
+
+/* If *PIDP is a composite process/thread id, convert it to a process id. */
+
+static void
+pid_to_prc (ptid_t *ptidp)
+{
+  ptid_t ptid;
+
+  ptid = *ptidp;
+  if (PD_TID (ptid))
+    *ptidp = pid_to_ptid (PIDGET (ptid));
+}
+
+/* pthdb callback: for <i> from 0 to COUNT, set SYMBOLS[<i>].addr to the
+   address of SYMBOLS[<i>].name. */
+
+static int
+pdc_symbol_addrs (pthdb_user_t user, pthdb_symbol_t *symbols, int count)
+{
+  struct minimal_symbol *ms;
+  int i;
+  char *name;
+
+  DBG2(("pdc_symbol_addrs (user = %ld, symbols = 0x%x, count = %d)",
+	user, symbols, count));
+
+  for (i = 0; i < count; i++)
+    {
+      name = symbols[i].name;
+      DBG2(("  symbols[%d].name = \"%s\"", i, name));
+
+      if (!*name)
+	symbols[i].addr = 0;
+      else
+	{
+	  if (!(ms = lookup_minimal_symbol (name, NULL, NULL)))
+	    {
+	      DBG2((" returning PDC_FAILURE"));
+	      return PDC_FAILURE;
+	    }
+	  symbols[i].addr = SYMBOL_VALUE_ADDRESS (ms);
+	}
+      DBG2(("  symbols[%d].addr = 0x%llx", i, symbols[i].addr));
+    }
+  DBG2((" returning PDC_SUCCESS"));
+  return PDC_SUCCESS;
+}
+
+/* Read registers call back function should be able to read the context */
+/* information of a debuggee kernel thread from an active process or from */
+/* a core file. The information should be formatted in context64 form for */
+/* both 32-bit and 64-bit process. If successful return 0, else non-zero */
+/* is returned. */
+static int
+pdc_read_regs (pthdb_user_t user, 
+	       pthdb_tid_t tid,
+	       unsigned long long flags,
+	       pthdb_context_t *context)
+{
+  /* this function doesn't appear to be used, so we could probably just */
+  /* return 0 here.  HOWEVER, if it is not defined, the OS will complain */
+  /* and several thread debug functions will fail. In case this is needed, */
+  /* I have implemented what I think it should do, however this code is */
+  /* untested. */
+  uint64_t gprs64[32];
+  uint32_t gprs32[32];
+  double fprs[32];
+  struct ptxsprs sprs64;
+  struct ptsprs sprs32;
+  
+  DBG2(("pdc_read_regs tid=%d flags=%llx\n", (int)tid, flags));
+
+  /* General-purpose registers. */
+  if (flags & PTHDB_FLAG_GPRS)
+    {
+      if (arch64)
+	{
+	  if (!ptrace64aix (PTT_READ_GPRS, tid, (unsigned long) gprs64, 0, NULL))
+	    memset (gprs64, 0, sizeof (gprs64));
+	  memcpy (context->gpr, gprs64, sizeof(gprs64));
+	}
+      else
+	{
+	  if (!ptrace32 (PTT_READ_GPRS, tid, gprs32, 0, NULL))
+	    memset (gprs32, 0, sizeof (gprs32));
+	  memcpy (context->gpr, gprs32, sizeof(gprs32));
+	}
+    }
+
+  /* Floating-point registers. */
+  if (flags & PTHDB_FLAG_FPRS)
+    {
+      if (!ptrace32 (PTT_READ_FPRS, tid, (int *) fprs, 0, NULL))
+	memset (fprs, 0, sizeof (fprs));
+      	  memcpy (context->fpr, fprs, sizeof(fprs));
+    }
+
+  /* Special-purpose registers. */
+  if (flags & PTHDB_FLAG_SPRS)
+    {
+      if (arch64)
+	{
+	  if (!ptrace64aix (PTT_READ_SPRS, tid, (unsigned long) &sprs64, 0, NULL))
+	    memset (&sprs64, 0, sizeof (sprs64));
+      	  memcpy (&context->msr, &sprs64, sizeof(sprs64));
+	}
+      else
+	{
+	  if (!ptrace32 (PTT_READ_SPRS, tid, (int *) &sprs32, 0, NULL))
+	    memset (&sprs32, 0, sizeof (sprs32));
+      	  memcpy (&context->msr, &sprs32, sizeof(sprs32));
+	}
+    }  
+  return 0;
+}
+
+/* Write register function should be able to write requested context */
+/* information to specified debuggee's kernel thread id. If successful */
+/* return 0, else non-zero is returned. */
+static int
+pdc_write_regs (pthdb_user_t user,
+		pthdb_tid_t tid,
+		unsigned long long flags,
+		pthdb_context_t *context)
+{ 
+  /* this function doesn't appear to be used, so we could probably just */
+  /* return 0 here.  HOWEVER, if it is not defined, the OS will complain */
+  /* and several thread debug functions will fail. In case this is needed, */
+  /* I have implemented what I think it should do, however this code is */
+  /* untested. */
+
+  DBG2(("pdc_write_regs tid=%d flags=%llx\n", (int)tid, flags));
+
+  /* General-purpose registers. */
+  if (flags & PTHDB_FLAG_GPRS)
+    {
+      if (arch64)
+	ptrace64aix (PTT_WRITE_GPRS, tid, (unsigned long)context->gpr, 0, NULL);
+      else
+	ptrace32 (PTT_WRITE_GPRS, tid, (int *)context->gpr, 0, NULL);
+    }
+
+ /* Floating-point registers. */
+  if (flags & PTHDB_FLAG_FPRS)
+    {
+      ptrace32 (PTT_WRITE_FPRS, tid, (int *)context->fpr, 0, NULL);
+    }
+
+  /* Special-purpose registers. */
+  if (flags & PTHDB_FLAG_SPRS)
+    {
+      if (arch64)
+	{
+	  ptrace64aix (PTT_WRITE_SPRS, tid, (unsigned long) &context->msr, 0, NULL);
+	}
+      else
+	{
+	  ptrace32 (PTT_WRITE_SPRS, tid, (int *)&context->msr, 0, NULL);
+	}
+    }
+  return 0;
+}
+
+/* pthdb callback: read LEN bytes from process ADDR into BUF. */
+
+static int
+pdc_read_data (pthdb_user_t user, void *buf, pthdb_addr_t addr, size_t len)
+{
+  int status, ret;
+
+  DBG2(("pdc_read_data (user = %ld, buf = 0x%x, addr = 0x%llx, len = %d)",
+	user, buf, addr, len));
+
+  status = target_read_memory (addr, buf, len);
+  ret = status == 0 ? PDC_SUCCESS : PDC_FAILURE;
+
+  DBG2(("  status=%d, returning %s", status, pd_status2str (ret)));
+  return ret;
+}
+
+/* pthdb callback: write LEN bytes from BUF to process ADDR. */
+
+static int
+pdc_write_data (pthdb_user_t user, void *buf, pthdb_addr_t addr, size_t len)
+{
+  int status, ret;
+
+  DBG2(("pdc_write_data (user = %ld, buf = 0x%x, addr = 0x%llx, len = %d)",
+	user, buf, addr, len));
+
+  status = target_write_memory (addr, buf, len);
+  ret = status == 0 ? PDC_SUCCESS : PDC_FAILURE;
+
+  DBG2(("  status=%d, returning %s", status, pd_status2str (ret)));
+  return ret;
+}
+
+/* pthdb callback: allocate a LEN-byte buffer and store a pointer to it in
+   BUFP. */
+
+static int
+pdc_alloc (pthdb_user_t user, size_t len, void **bufp)
+{
+  DBG2(("pdc_alloc (user = %ld, len = %d, bufp = 0x%x)", user, len, bufp));
+  *bufp = xmalloc (len);
+  DBG2(("  malloc returned 0x%x", *bufp));
+  /* Note: xmalloc() can't return 0; therefore PDC_FAILURE will never be
+     returned.  */
+  return *bufp ? PDC_SUCCESS : PDC_FAILURE;
+}
+
+/* pthdb callback: reallocate BUF, which was allocated by the alloc or realloc
+   callback, so that it contains LEN bytes, and store a pointer to the result
+   in BUFP. */
+
+static int
+pdc_realloc (pthdb_user_t user, void *buf, size_t len, void **bufp)
+{
+  DBG2(("pdc_realloc (user = %ld, buf = 0x%x, len = %d, bufp = 0x%x)",
+	user, buf, len, bufp));
+  *bufp = realloc (buf, len);
+  DBG2(("  realloc returned 0x%x", *bufp));
+  return *bufp ? PDC_SUCCESS : PDC_FAILURE;
+}
+
+/* pthdb callback: free BUF, which was allocated by the alloc or realloc
+   callback. */
+
+static int
+pdc_dealloc (pthdb_user_t user, void *buf)
+{
+  DBG2(("pdc_free (user = %ld, buf = 0x%x)", user, buf));
+  xfree (buf);
+  return PDC_SUCCESS;
+}
+
+/* Return a printable representation of pthread STATE. */
+
+static char *
+state2str (pthdb_state_t state)
+{
+  switch (state)
+    {
+    case PST_IDLE:	return "idle";		/* being created */
+    case PST_RUN:	return "running";	/* running */
+    case PST_SLEEP:	return "sleeping";	/* awaiting an event */
+    case PST_READY:	return "ready";		/* runnable */
+    case PST_TERM:	return "finished";	/* awaiting a join/detach */
+    default:		return "unknown";
+    }
+}
+
+/* qsort() comparison function for sorting pd_thread structs by pthid. */
+
+static int
+pcmp (const void *p1v, const void *p2v)
+{
+  struct pd_thread *p1 = (struct pd_thread *) p1v;
+  struct pd_thread *p2 = (struct pd_thread *) p2v;
+  return p1->pthid < p2->pthid ? -1 : p1->pthid > p2->pthid;
+}
+
+/* iterate_over_threads() callback for counting GDB threads. */
+
+static int
+giter_count (struct thread_info *thread, void *countp)
+{
+  (*(int *) countp)++;
+  return 0;
+}
+
+/* iterate_over_threads() callback for accumulating GDB thread pids. */
+
+static int
+giter_accum (struct thread_info *thread, void *bufp)
+{
+  **(struct thread_info ***) bufp = thread;
+  (*(struct thread_info ***) bufp)++;
+  return 0;
+}
+
+/* ptid comparison function */
+static int
+ptid_cmp (ptid_t ptid1, ptid_t ptid2)
+{
+  int pid1, pid2;
+
+  if (ptid_get_pid (ptid1) < ptid_get_pid (ptid2))
+    return -1;
+  else if (ptid_get_pid (ptid1) > ptid_get_pid (ptid2))
+    return 1;
+  else if (ptid_get_tid (ptid1) < ptid_get_tid (ptid2))
+    return -1;
+  else if (ptid_get_tid (ptid1) > ptid_get_tid (ptid2))
+    return 1;
+  else if (ptid_get_lwp (ptid1) < ptid_get_lwp (ptid2))
+    return -1;
+  else if (ptid_get_lwp (ptid1) > ptid_get_lwp (ptid2))
+    return 1;
+  else
+    return 0;
+}
+
+/* qsort() comparison function for sorting thread_info structs by pid. */
+
+static int
+gcmp (const void *t1v, const void *t2v)
+{
+  struct thread_info *t1 = *(struct thread_info **) t1v;
+  struct thread_info *t2 = *(struct thread_info **) t2v;
+  return ptid_cmp (t1->ptid, t2->ptid);
+}
+
+/* Synchronize GDB's thread list with libpthdebug's.
+
+   There are some benefits of doing this every time the inferior stops:
+
+     - allows users to run thread-specific commands without needing to run
+       "info threads" first
+
+     - helps pthdb_tid_pthread() work properly (see "libpthdebug
+       peculiarities" at the top of this module)
+
+     - simplifies the demands placed on libpthdebug, which seems to have
+       difficulty with certain call patterns */
+
+static void
+sync_threadlists (void)
+{
+  int cmd, status, infpid;
+  int pcount, psize, pi, gcount, gi;
+  struct pd_thread *pbuf;
+  struct thread_info **gbuf, **g, *thread;
+  pthdb_pthread_t pdtid;
+  pthread_t pthid;
+  pthdb_tid_t tid;
+  ptid_t pptid, gptid;
+
+  /* Accumulate an array of libpthdebug threads sorted by pthread id. */
+
+  pcount = 0;
+  psize = 1;
+  pbuf = (struct pd_thread *) xmalloc (psize * sizeof *pbuf);
+
+  for (cmd = PTHDB_LIST_FIRST;; cmd = PTHDB_LIST_NEXT)
+    {
+      status = pthdb_pthread (pd_session, &pdtid, cmd);
+      if (status != PTHDB_SUCCESS || pdtid == PTHDB_INVALID_PTHREAD)
+	break;
+
+      status = pthdb_pthread_ptid (pd_session, pdtid, &pthid);
+      if (status != PTHDB_SUCCESS || pthid == PTHDB_INVALID_PTID)
+	continue;
+
+      if (pcount == psize)
+	{
+	  psize *= 2;
+	  pbuf = (struct pd_thread *) xrealloc (pbuf, psize * sizeof *pbuf);
+	}
+      pbuf[pcount].pdtid = pdtid;
+      pbuf[pcount].pthid = pthid;
+      pcount++;
+    }
+
+  for (pi = 0; pi < pcount; pi++)
+    {
+      status = pthdb_pthread_tid (pd_session, pbuf[pi].pdtid, &tid);
+      if (status != PTHDB_SUCCESS)
+	tid = PTHDB_INVALID_TID;
+      pbuf[pi].tid = tid;
+    }
+
+  qsort (pbuf, pcount, sizeof *pbuf, pcmp);
+
+  /* Accumulate an array of GDB threads sorted by pid. */
+
+  gcount = 0;
+  iterate_over_threads (giter_count, &gcount);
+  g = gbuf = (struct thread_info **) xmalloc (gcount * sizeof *gbuf);
+  iterate_over_threads (giter_accum, &g);
+  qsort (gbuf, gcount, sizeof *gbuf, gcmp);
+
+  /* Apply differences between the two arrays to GDB's thread list. */
+
+  infpid = PIDGET (inferior_ptid);
+  for (pi = gi = 0; pi < pcount || gi < gcount;)
+    {
+      pptid = BUILD_THREAD (pbuf[pi].pthid, infpid);
+      gptid = gbuf[gi]->ptid;
+      pdtid = pbuf[pi].pdtid;
+      tid = pbuf[pi].tid;
+
+      if (pi == pcount)
+	goto del;
+      if (gi == gcount)
+	goto add;
+
+      if (ptid_equal (pptid, gptid))
+	{
+	  gbuf[gi]->private->pdtid = pdtid;
+	  gbuf[gi]->private->tid = tid;
+	  pi++;
+	  gi++;
+	}
+      else if (ptid_cmp (pptid, gptid) > 0)
+	{
+	del:
+	  delete_thread (gptid);
+	  gi++;
+	}
+      else
+	{
+	add:
+	  thread = add_thread (pptid);
+	  thread->private = xmalloc (sizeof (struct private_thread_info));
+	  thread->private->pdtid = pdtid;
+	  thread->private->tid = tid;
+	  pi++;
+	}
+
+    }
+
+  xfree (pbuf);
+  xfree (gbuf);
+}
+
+/* iterate_over_threads() callback for locating a thread whose kernel thread
+   just received a trap signal. */
+
+static int
+iter_trap (struct thread_info *thread, void *unused)
+{
+  struct thrdsinfo64 thrinf;
+  pthdb_tid_t tid;
+
+  /* getthrds(3) isn't prototyped in any AIX 4.3.3 #include file. */
+  extern int getthrds (pid_t, struct thrdsinfo64 *, int, pthdb_tid_t *, int);
+
+  tid = thread->private->tid;
+  if (tid == PTHDB_INVALID_TID)
+    return 0;
+
+  if (getthrds (PIDGET (inferior_ptid), &thrinf, sizeof (thrinf), &tid, 1) != 1)
+    return 0;
+
+  return thrinf.ti_cursig == SIGTRAP;
+}
+
+/* Synchronize libpthdebug's state with the inferior and with GDB, generate a
+   composite process/thread <pid> for the current thread, set inferior_ptid to
+   <pid> if SET_INFPID, and return <pid>. */
+
+static ptid_t
+pd_update (int set_infpid)
+{
+  int status;
+  ptid_t ptid;
+  struct thread_info *thread;
+
+  if (!pd_active)
+    return inferior_ptid;
+
+  status = pthdb_session_update (pd_session);
+  if (status != PTHDB_SUCCESS)
+    return inferior_ptid;
+
+  sync_threadlists ();
+
+  /* Define "current thread" as one that just received a trap signal. */
+
+  thread = iterate_over_threads (iter_trap, NULL);
+  if (!thread)
+    ptid = inferior_ptid;
+  else
+    {
+      ptid = thread->ptid;
+      if (set_infpid)
+	inferior_ptid = ptid;
+    }
+  return ptid;
+}
+
+/* Try to start debugging threads in the current process.  If successful and
+   SET_INFPID, set inferior_ptid to reflect the current thread. */
+
+static ptid_t
+pd_activate (int set_infpid)
+{
+  int status;
+		
+  status = pthdb_session_init (PD_USER, arch64 ? PEM_64BIT : PEM_32BIT,
+			       PTHDB_FLAG_REGS, &pd_callbacks, &pd_session);
+  if (status != PTHDB_SUCCESS)
+    {
+      return inferior_ptid;
+    }
+  pd_active = 1;
+  return pd_update (set_infpid);
+}
+
+/* Undo the effects of pd_activate(). */
+
+static void
+pd_deactivate (void)
+{
+  if (!pd_active)
+    return;
+  pthdb_session_destroy (pd_session);
+  
+  pid_to_prc (&inferior_ptid);
+  pd_active = 0;
+}
+
+/* An object file has just been loaded.  Check whether the current application
+   is pthreaded, and if so, prepare for thread debugging. */
+
+static void
+pd_enable (void)
+{
+  int status;
+  char *stub_name;
+  struct minimal_symbol *ms;
+
+  /* Don't initialize twice. */
+  if (pd_able)
+    return;
+
+  /* Check application word size. */
+  arch64 = REGISTER_RAW_SIZE (0) == 8;
+
+  /* Check whether the application is pthreaded. */
+  stub_name = NULL;
+  status = pthdb_session_pthreaded (PD_USER, PTHDB_FLAG_REGS, &pd_callbacks,
+				    &stub_name);
+  if ((status != PTHDB_SUCCESS && status != PTHDB_NOT_PTHREADED) || !stub_name)
+    return;
+
+  /* Set a breakpoint on the returned stub function. */
+  if (!(ms = lookup_minimal_symbol (stub_name, NULL, NULL)))
+    return;
+  pd_brk_addr = SYMBOL_VALUE_ADDRESS (ms);
+  if (!create_thread_event_breakpoint (pd_brk_addr))
+    return;
+
+  /* Prepare for thread debugging. */
+  base_ops = current_target;
+  push_target (&ops);
+  pd_able = 1;
+
+  /* If we're debugging a core file or an attached inferior, the pthread
+     library may already have been initialized, so try to activate thread
+     debugging. */
+  pd_activate (1);
+}
+
+/* Undo the effects of pd_enable(). */
+
+static void
+pd_disable (void)
+{
+  if (!pd_able)
+    return;
+  if (pd_active)
+    pd_deactivate ();
+  pd_able = 0;
+  unpush_target (&ops);
+}
+
+/* target_new_objfile_hook callback.
+
+   If OBJFILE is non-null, check whether a threaded application is being
+   debugged, and if so, prepare for thread debugging.
+
+   If OBJFILE is null, stop debugging threads. */
+
+static void
+new_objfile (struct objfile *objfile)
+{
+  if (objfile)
+    pd_enable ();
+  else
+    pd_disable ();
+
+  if (target_new_objfile_chain)
+    target_new_objfile_chain (objfile);
+}
+
+/* Attach to process specified by ARGS. */
+
+static void
+ops_attach (char *args, int from_tty)
+{
+  base_ops.to_attach (args, from_tty);
+  pd_activate (1);
+}
+
+/* Detach from the process attached to by ops_attach(). */
+
+static void
+ops_detach (char *args, int from_tty)
+{
+  pd_deactivate ();
+  base_ops.to_detach (args, from_tty);
+}
+
+/* Tell the inferior process to continue running thread PID if != -1
+   and all threads otherwise. */
+
+static void
+ops_resume (ptid_t ptid, int step, enum target_signal sig)
+{
+  struct thread_info *thread;
+  pthdb_tid_t tid[2];
+
+  if (!PD_TID (ptid))
+    CALL_BASE (base_ops.to_resume (ptid, step, sig));
+  else
+    {
+      thread = find_thread_pid (ptid);
+      if (!thread)
+	error ("aix-thread resume: unknown pthread %ld", TIDGET (ptid));
+
+      tid[0] = thread->private->tid;
+      if (tid[0] == PTHDB_INVALID_TID)
+	error ("aix-thread resume: no tid for pthread %ld", TIDGET (ptid));
+      tid[1] = 0;
+
+      if (arch64)
+	ptrace64aix (PTT_CONTINUE, tid[0], 1, target_signal_to_host (sig), (int *)tid);
+      else
+	ptrace32 (PTT_CONTINUE, tid[0], (int *) 1,
+		  target_signal_to_host (sig), (int *)tid);
+    }
+}
+
+/* Wait for thread/process ID if != -1 or for any thread otherwise.  If an
+   error occurs, return -1, else return the pid of the stopped thread. */
+
+static ptid_t
+ops_wait (ptid_t ptid, struct target_waitstatus *status)
+{
+  pid_to_prc (&ptid);
+  CALL_BASE (ptid = base_ops.to_wait (ptid, status));
+  if (PIDGET (ptid) == -1)
+    return pid_to_ptid (-1);
+
+  /* Check whether libpthdebug might be ready to be initialized. */
+  if (!pd_active && status->kind == TARGET_WAITKIND_STOPPED &&
+      status->value.sig == TARGET_SIGNAL_TRAP &&
+      read_pc_pid (ptid) - DECR_PC_AFTER_BREAK == pd_brk_addr)
+    return pd_activate (0);
+
+  return pd_update (0);
+}
+
+/* Record that the 64-bit general-purpose registers contain VALS. */
+
+static void
+supply_gprs64 (uint64_t *vals)
+{
+  int regno;
+
+  for (regno = 0; regno < 32; regno++)
+    supply_register (regno, (char *) (vals + regno));
+}
+
+/* Record that 32-bit register REGNO contains VAL. */
+
+static void
+supply_reg32 (int regno, uint32_t val)
+{
+  supply_register (regno, (char *) &val);
+}
+
+/* Record that the floating-point registers contain VALS. */
+
+static void
+supply_fprs (double *vals)
+{
+  int regno;
+
+  for (regno = 0; regno < 32; regno++)
+    supply_register (regno + FP0_REGNUM, (char *) (vals + regno));
+}
+
+/* Record that the special registers contain the specified 64-bit and 32-bit
+   values. */
+
+static void
+supply_sprs64 (uint64_t iar, uint64_t msr, uint32_t cr,
+	       uint64_t lr, uint64_t ctr, uint32_t xer)
+{
+  int regno = FIRST_UISA_SP_REGNUM;
+  supply_register (regno, (char *) &iar);
+  supply_register (regno + 1, (char *) &msr);
+  supply_register (regno + 2, (char *) &cr);
+  supply_register (regno + 3, (char *) &lr);
+  supply_register (regno + 4, (char *) &ctr);
+  supply_register (regno + 5, (char *) &xer);
+}
+
+/* Record that the special registers contain the specified 32-bit values. */
+
+static void
+supply_sprs32 (uint32_t iar, uint32_t msr, uint32_t cr,
+	       uint32_t lr, uint32_t ctr, uint32_t xer)
+{
+  int regno = FIRST_UISA_SP_REGNUM;
+  supply_register (regno, (char *) &iar);
+  supply_register (regno + 1, (char *) &msr);
+  supply_register (regno + 2, (char *) &cr);
+  supply_register (regno + 3, (char *) &lr);
+  supply_register (regno + 4, (char *) &ctr);
+  supply_register (regno + 5, (char *) &xer);
+}
+
+/* Fetch all registers from pthread PDTID, which doesn't have a kernel
+   thread.
+
+   There's no way to query a single register from a non-kernel pthread,
+   so there's no need for a single-register version of this function. */
+
+static void
+fetch_regs_lib (pthdb_pthread_t pdtid)
+{
+  int status, i;
+  pthdb_context_t ctx;
+
+  DBG2 (("fetch_regs_lib %lx\n", (long)pdtid));
+  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  if (status != PTHDB_SUCCESS)
+    PD_ERROR ("fetch_registers: pthdb_pthread_context", status);
+
+  /* General-purpose registers. */
+
+  if (arch64)
+    supply_gprs64 (ctx.gpr);
+  else
+    for (i = 0; i < 32; i++)
+      supply_reg32 (i, ctx.gpr[i]);
+
+  /* Floating-point registers. */
+
+  supply_fprs (ctx.fpr);
+
+  /* Special registers. */
+
+  if (arch64)
+    supply_sprs64 (ctx.iar, ctx.msr, ctx.cr, ctx.lr, ctx.ctr, ctx.xer);
+  else
+    supply_sprs32 (ctx.iar, ctx.msr, ctx.cr, ctx.lr, ctx.ctr, ctx.xer);
+}
+
+/* Fetch register REGNO if != -1 or all registers otherwise from kernel thread
+   TID.
+
+   AIX provides a way to query all of a kernel thread's GPRs, FPRs, or SPRs,
+   but there's no way to query individual registers within those groups.
+   Therefore, if REGNO != -1, this function fetches an entire group.
+
+   Unfortunately, kernel thread register queries often fail with EPERM,
+   indicating that the thread is in kernel space.  This breaks backtraces of
+   threads other than the current one.  To make that breakage obvious without
+   throwing an error to top level (which is bad e.g. during "info threads"
+   output), zero registers that can't be retrieved. */
+
+static void
+fetch_regs_kern (int regno, pthdb_tid_t tid)
+{
+  uint64_t gprs64[32];
+  uint32_t gprs32[32];
+  double fprs[32];
+  struct ptxsprs sprs64;
+  struct ptsprs sprs32;
+  int i;
+
+  DBG2 (("fetch_regs_kern tid=%lx regno=%d arch64=%d\n", (long)tid, regno, arch64));
+
+  /* General-purpose registers. */
+  if (regno == -1 || regno < FP0_REGNUM)
+    {
+      if (arch64)
+	{
+	  if (!ptrace64aix (PTT_READ_GPRS, tid, (unsigned long) gprs64, 0, NULL))
+	    memset (gprs64, 0, sizeof (gprs64));
+	  supply_gprs64 (gprs64);
+	}
+      else
+	{
+	  if (!ptrace32 (PTT_READ_GPRS, tid, gprs32, 0, NULL))
+	    memset (gprs32, 0, sizeof (gprs32));
+	  for (i = 0; i < 32; i++)
+	    supply_reg32 (i, gprs32[i]);
+	}
+    }
+
+  /* Floating-point registers. */
+
+  if (regno == -1 || (regno >= FP0_REGNUM && regno <= FPLAST_REGNUM))
+    {
+      if (!ptrace32 (PTT_READ_FPRS, tid, (int *) fprs, 0, NULL))
+	memset (fprs, 0, sizeof (fprs));
+      supply_fprs (fprs);
+    }
+
+  /* Special-purpose registers. */
+
+  if (regno == -1 || (regno > FPLAST_REGNUM && regno <= LAST_UISA_SP_REGNUM))
+    {
+      if (arch64)
+	{
+	  if (!ptrace64aix (PTT_READ_SPRS, tid, (unsigned long) &sprs64, 0, NULL))
+	    memset (&sprs64, 0, sizeof (sprs64));
+	  supply_sprs64 (sprs64.pt_iar, sprs64.pt_msr, sprs64.pt_cr,
+			 sprs64.pt_lr, sprs64.pt_ctr, sprs64.pt_xer);
+	}
+      else
+	{
+	  if (!ptrace32 (PTT_READ_SPRS, tid, (int *) &sprs32, 0, NULL))
+	    memset (&sprs32, 0, sizeof (sprs32));
+	  supply_sprs32 (sprs32.pt_iar, sprs32.pt_msr, sprs32.pt_cr,
+			 sprs32.pt_lr, sprs32.pt_ctr, sprs32.pt_xer);
+
+	  if (REGISTER_RAW_SIZE (LAST_UISA_SP_REGNUM))
+	    supply_register (LAST_UISA_SP_REGNUM, (char *) &sprs32.pt_mq);
+	}
+    }
+}
+
+/* Fetch register REGNO if != -1 or all registers otherwise in the
+   thread/process specified by inferior_ptid. */
+
+static void
+ops_fetch_registers (int regno)
+{
+  struct thread_info *thread;
+  pthdb_tid_t tid;
+
+  if (!PD_TID (inferior_ptid))
+    base_ops.to_fetch_registers (regno);
+  else
+    {
+      thread = find_thread_pid (inferior_ptid);
+      tid = thread->private->tid;
+
+      if (tid == PTHDB_INVALID_TID)
+	fetch_regs_lib (thread->private->pdtid);
+      else
+	fetch_regs_kern (regno, tid);
+    }
+}
+
+/* Store the special registers into the specified 64-bit and 32-bit
+   locations. */
+
+static void
+fill_sprs64 (uint64_t *iar, uint64_t *msr, uint32_t *cr,
+	     uint64_t *lr, uint64_t *ctr, uint32_t *xer)
+{
+  int regno = FIRST_UISA_SP_REGNUM;
+  *iar = read_register (regno);
+  *msr = read_register (regno + 1);
+  *cr = read_register (regno + 2);
+  *lr = read_register (regno + 3);
+  *ctr = read_register (regno + 4);
+  *xer = read_register (regno + 5);
+}
+
+/* Store all registers into pthread PDTID, which doesn't have a kernel
+   thread.
+
+   It's possible to store a single register into a non-kernel pthread, but I
+   doubt it's worth the effort. */
+
+static void
+store_regs_lib (pthdb_pthread_t pdtid)
+{
+  int status, i;
+  pthdb_context_t ctx;
+
+  DBG2 (("store_regs_lib %lx\n", (long)pdtid));
+
+  /* Retrieve the thread's current context for its non-register values. */
+  status = pthdb_pthread_context (pd_session, pdtid, &ctx);
+  if (status != PTHDB_SUCCESS)
+    PD_ERROR ("store_registers: pthdb_pthread_context", status);
+
+  /* General-purpose registers. */
+
+  for (i = 0; i < 32; i++)
+    ctx.gpr[i] = read_register (i);
+
+  /* Floating-point registers. */
+
+  for (i = 0; i < 32; i++)
+    ctx.fpr[i] = *(double *) &registers[REGISTER_BYTE (FP0_REGNUM + i)];
+
+  /* Special registers. */
+
+  fill_sprs64 (&ctx.iar, &ctx.msr, &ctx.cr, &ctx.lr, &ctx.ctr, &ctx.xer);
+
+  status = pthdb_pthread_setcontext (pd_session, pdtid, &ctx);
+  if (status != PTHDB_SUCCESS)
+    PD_ERROR ("store_registers: pthdb_pthread_setcontext", status);
+}
+
+/* Store register REGNO if != -1 or all registers otherwise into kernel
+   thread TID.
+
+   AIX provides a way to set all of a kernel thread's GPRs, FPRs, or SPRs, but
+   there's no way to set individual registers within those groups.  Therefore,
+   if REGNO != -1, this function stores an entire group. */
+
+static void
+store_regs_kern (int regno, pthdb_tid_t tid)
+{
+  struct ptxsprs sprs64;
+  struct ptsprs sprs32;
+  char *regp;
+
+  DBG2 (("store_regs_kern tid=%lx regno=%d\n", (long)tid, regno));
+
+  /* General-purpose registers. */
+  if (regno == -1 || regno < FP0_REGNUM)
+    {
+      regp = &registers[REGISTER_BYTE (0)];
+      if (arch64)
+	ptrace64aix (PTT_WRITE_GPRS, tid, (unsigned long) regp, 0, NULL);
+      else
+	ptrace32 (PTT_WRITE_GPRS, tid, (int *) regp, 0, NULL);
+    }
+
+  /* Floating-point registers. */
+
+  if (regno == -1 || (regno >= FP0_REGNUM && regno <= FPLAST_REGNUM))
+    {
+      regp = &registers[REGISTER_BYTE (FP0_REGNUM)];
+      ptrace32 (PTT_WRITE_FPRS, tid, (int *) regp, 0, NULL);
+    }
+
+  /* Special-purpose registers. */
+
+  if (regno == -1 || (regno > FPLAST_REGNUM && regno <= LAST_UISA_SP_REGNUM))
+    {
+      if (arch64)
+	{
+	  ptrace64aix (PTT_READ_SPRS, tid, (unsigned long) &sprs64, 0, NULL);
+	  fill_sprs64 (&sprs64.pt_iar, &sprs64.pt_msr, &sprs64.pt_cr,
+		       &sprs64.pt_lr, &sprs64.pt_ctr, &sprs64.pt_xer);
+	  ptrace64aix (PTT_WRITE_SPRS, tid, (unsigned long) &sprs64, 0, NULL);
+	}
+      else
+	{
+	  ptrace32 (PTT_READ_SPRS, tid, (int *) &sprs32, 0, NULL);
+
+	  regno = FIRST_UISA_SP_REGNUM;
+	  sprs32.pt_iar = read_register (regno);
+	  sprs32.pt_msr = read_register (regno + 1);
+	  sprs32.pt_cr = read_register (regno + 2);
+	  sprs32.pt_lr = read_register (regno + 3);
+	  sprs32.pt_ctr = read_register (regno + 4);
+	  sprs32.pt_xer = read_register (regno + 5);
+
+	  if (REGISTER_RAW_SIZE (LAST_UISA_SP_REGNUM))
+	    sprs32.pt_mq = read_register (LAST_UISA_SP_REGNUM);
+
+	  ptrace32 (PTT_WRITE_SPRS, tid, (int *) &sprs32, 0, NULL);
+	}
+    }
+}
+
+/* Store gdb's current view of the register set into the thread/process
+   specified by inferior_ptid. */
+
+static void
+ops_store_registers (int regno)
+{
+  struct thread_info *thread;
+  pthdb_tid_t tid;
+
+  if (!PD_TID (inferior_ptid))
+    base_ops.to_store_registers (regno);
+  else
+    {
+      thread = find_thread_pid (inferior_ptid);
+      tid = thread->private->tid;
+
+      if (tid == PTHDB_INVALID_TID)
+	store_regs_lib (thread->private->pdtid);
+      else
+	store_regs_kern (regno, tid);
+    }
+}
+
+/* Prepare to modify the registers array. */
+
+static void
+ops_prepare_to_store (void)
+{
+  if (!PD_TID (inferior_ptid))
+    base_ops.to_prepare_to_store ();
+  else
+    read_register_bytes (0, NULL, REGISTER_BYTES);
+}
+
+/* Transfer LEN bytes of memory from GDB address MYADDR to target address
+   MEMADDR if WRITE and vice versa otherwise. */
+
+static int
+ops_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
+                 struct mem_attrib *attrib,
+		 struct target_ops *target)
+{
+  int n;
+
+  CALL_BASE (n = base_ops.to_xfer_memory (memaddr, myaddr, len, write,
+					  attrib, &base_ops));
+  return n;
+}
+
+/* Kill and forget about the inferior process. */
+
+static void
+ops_kill (void)
+{
+  CALL_BASE (base_ops.to_kill ());
+}
+
+/* Clean up after the inferior exits. */
+
+static void
+ops_mourn_inferior (void)
+{
+  pd_deactivate ();
+  base_ops.to_mourn_inferior ();
+}
+
+/* Return whether thread PID is still valid. */
+
+static int
+ops_thread_alive (ptid_t ptid)
+{
+  if (!PD_TID (ptid))
+    return base_ops.to_thread_alive (ptid);
+
+  /* We update the thread list every time the child stops, so all valid
+     threads should be in the thread list. */
+  return in_thread_list (ptid);
+}
+
+/* Return a printable representation of composite PID for use in "info
+   threads" output. */
+
+static char *
+ops_pid_to_str (ptid_t ptid)
+{
+  static char *ret = NULL;
+
+  if (!PD_TID (ptid))
+    return base_ops.to_pid_to_str (ptid);
+
+  /* Free previous return value; a new one will be allocated by
+     xasprintf().  */
+  xfree (ret);
+
+  xasprintf (&ret, "Thread %ld", ptid_get_tid (ptid));
+  return ret;
+}
+
+/* Return a printable representation of extra information about THREAD, for
+   use in "info threads" output. */
+
+static char *
+ops_extra_thread_info (struct thread_info *thread)
+{
+  struct ui_file *buf;
+  int status;
+  pthdb_pthread_t pdtid;
+  pthdb_tid_t tid;
+  pthdb_state_t state;
+  pthdb_suspendstate_t suspendstate;
+  pthdb_detachstate_t detachstate;
+  int cancelpend;
+  long length;
+  static char *ret = NULL;
+
+  if (!PD_TID (thread->ptid))
+    return NULL;
+
+  buf = mem_fileopen ();
+
+  pdtid = thread->private->pdtid;
+  tid = thread->private->tid;
+
+  if (tid != PTHDB_INVALID_TID)
+    fprintf_unfiltered (buf, "tid %d", tid);
+
+  status = pthdb_pthread_state (pd_session, pdtid, &state);
+  if (status != PTHDB_SUCCESS)
+    state = PST_NOTSUP;
+  fprintf_unfiltered (buf, ", %s", state2str (state));
+
+  status = pthdb_pthread_suspendstate (pd_session, pdtid, &suspendstate);
+  if (status == PTHDB_SUCCESS && suspendstate == PSS_SUSPENDED)
+    fprintf_unfiltered (buf, ", suspended");
+
+  status = pthdb_pthread_detachstate (pd_session, pdtid, &detachstate);
+  if (status == PTHDB_SUCCESS && detachstate == PDS_DETACHED)
+    fprintf_unfiltered (buf, ", detached");
+
+  pthdb_pthread_cancelpend (pd_session, pdtid, &cancelpend);
+  if (status == PTHDB_SUCCESS && cancelpend)
+    fprintf_unfiltered (buf, ", cancel pending");
+
+  ui_file_write (buf, "", 1);
+
+  xfree (ret);			/* Free old buffer.  */
+
+  ret = ui_file_xstrdup (buf, &length);
+  ui_file_delete (buf);
+
+  return ret;
+}
+
+/* Initialize target ops. */
+
+static void
+init_ops (void)
+{
+  ops.to_shortname          = "aix-threads";
+  ops.to_longname           = "AIX pthread support";
+  ops.to_doc                = "AIX pthread support";
+
+  ops.to_attach             = ops_attach;
+  ops.to_detach             = ops_detach;
+  ops.to_resume             = ops_resume;
+  ops.to_wait               = ops_wait;
+  ops.to_fetch_registers    = ops_fetch_registers;
+  ops.to_store_registers    = ops_store_registers;
+  ops.to_prepare_to_store   = ops_prepare_to_store;
+  ops.to_xfer_memory        = ops_xfer_memory;
+  /* No need for ops.to_create_inferior, because we activate thread debugging
+     when the inferior reaches pd_brk_addr. */
+  ops.to_kill               = ops_kill;
+  ops.to_mourn_inferior     = ops_mourn_inferior;
+  ops.to_thread_alive       = ops_thread_alive;
+  ops.to_pid_to_str         = ops_pid_to_str;
+  ops.to_extra_thread_info  = ops_extra_thread_info;
+  ops.to_stratum            = thread_stratum;
+  ops.to_magic              = OPS_MAGIC;
+}
+
+/* Module startup initialization function, automagically called by
+   init.c. */
+
+void
+_initialize_aix_thread (void)
+{
+  init_ops ();
+  add_target (&ops);
+
+  /* Notice when object files get loaded and unloaded. */
+  target_new_objfile_chain = target_new_objfile_hook;
+  target_new_objfile_hook = new_objfile;
+}