Support loading two libthread_db DSOs.  In this case, the LinuxThreads
and NPTL ones.

Index: gdb-6.3/gdb/thread-db.c
===================================================================
--- gdb-6.3.orig/gdb/thread-db.c	2004-11-10 10:46:24.000000000 -0500
+++ gdb-6.3/gdb/thread-db.c	2004-11-10 11:22:34.858812426 -0500
@@ -79,53 +79,63 @@ static td_thragent_t *thread_agent;
 
 /* Pointers to the libthread_db functions.  */
 
-static td_err_e (*td_init_p) (void);
+struct thread_db_pointers
+{
+  const char *filename;
+
+  td_err_e (*td_init_p) (void);
 
-static td_err_e (*td_ta_new_p) (struct ps_prochandle * ps,
-				td_thragent_t **ta);
-static td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
-				       td_thrhandle_t *__th);
-static td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta,
-					lwpid_t lwpid, td_thrhandle_t *th);
-static td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
-				     td_thr_iter_f *callback, void *cbdata_p,
-				     td_thr_state_e state, int ti_pri,
-				     sigset_t *ti_sigmask_p,
-				     unsigned int ti_user_flags);
-static td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
-				       td_event_e event, td_notify_t *ptr);
-static td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
-				      td_thr_events_t *event);
-static td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
-					 td_event_msg_t *msg);
-
-static td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
-static td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
-				      td_thrinfo_t *infop);
-static td_err_e (*td_thr_getfpregs_p) (const td_thrhandle_t *th,
-				       gdb_prfpregset_t *regset);
-static td_err_e (*td_thr_getgregs_p) (const td_thrhandle_t *th,
-				      prgregset_t gregs);
-static td_err_e (*td_thr_setfpregs_p) (const td_thrhandle_t *th,
-				       const gdb_prfpregset_t *fpregs);
-static td_err_e (*td_thr_setgregs_p) (const td_thrhandle_t *th,
-				      prgregset_t gregs);
-static td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
-					  int event);
-
-static td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
-					  void *map_address,
-					  size_t offset, void **address);
+  td_err_e (*td_ta_new_p) (struct ps_prochandle * ps,
+			   td_thragent_t **ta);
+  td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
+				  td_thrhandle_t *__th);
+  td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta,
+				   lwpid_t lwpid, td_thrhandle_t *th);
+
+  td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
+				td_thr_iter_f *callback, void *cbdata_p,
+				td_thr_state_e state, int ti_pri,
+				sigset_t *ti_sigmask_p,
+				unsigned int ti_user_flags);
+  td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
+				  td_event_e event, td_notify_t *ptr);
+  td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
+				 td_thr_events_t *event);
+  td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
+				    td_event_msg_t *msg);
+
+  td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
+  td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
+				 td_thrinfo_t *infop);
+  td_err_e (*td_thr_getfpregs_p) (const td_thrhandle_t *th,
+				  gdb_prfpregset_t *regset);
+  td_err_e (*td_thr_getgregs_p) (const td_thrhandle_t *th,
+				 prgregset_t gregs);
+  td_err_e (*td_thr_setfpregs_p) (const td_thrhandle_t *th,
+				  const gdb_prfpregset_t *fpregs);
+  td_err_e (*td_thr_setgregs_p) (const td_thrhandle_t *th,
+				 prgregset_t gregs);
+  td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
+				     int event);
+
+  td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
+				     void *map_address,
+				     size_t offset, void **address);
+
+  struct thread_db_pointers *next;
+};
 
 /* Location of the thread creation event breakpoint.  The code at this
    location in the child process will be called by the pthread library
    whenever a new thread is created.  By setting a special breakpoint
    at this location, GDB can detect when a new thread is created.  We
    obtain this location via the td_ta_event_addr call.  */
-static CORE_ADDR td_create_bp_addr;
+CORE_ADDR td_create_bp_addr;
 
 /* Location of the thread death event breakpoint.  */
-static CORE_ADDR td_death_bp_addr;
+CORE_ADDR td_death_bp_addr;
+
+static struct thread_db_pointers *current_pointers, *all_pointers;
 
 /* Prototypes for local functions.  */
 static void thread_db_find_new_threads (void);
@@ -262,7 +272,7 @@ thread_get_info_callback (const td_thrha
   struct thread_info *thread_info;
   ptid_t thread_ptid;
 
-  err = td_thr_get_info_p (thp, &ti);
+  err = current_pointers->td_thr_get_info_p (thp, &ti);
   if (err != TD_OK)
     error ("thread_get_info_callback: cannot get thread info: %s",
 	   thread_db_err_str (err));
@@ -316,8 +326,9 @@ thread_db_map_id2thr (struct thread_info
   if (thread_info->private->th_valid)
     return;
 
-  err = td_ta_map_id2thr_p (thread_agent, GET_THREAD (thread_info->ptid),
-			    &thread_info->private->th);
+  err = current_pointers->td_ta_map_id2thr_p (thread_agent,
+					      GET_THREAD (thread_info->ptid),
+					      &thread_info->private->th);
   if (err != TD_OK)
     {
       if (fatal)
@@ -340,8 +351,8 @@ thread_db_get_info (struct thread_info *
   if (!thread_info->private->th_valid)
     thread_db_map_id2thr (thread_info, 1);
 
-  err =
-    td_thr_get_info_p (&thread_info->private->th, &thread_info->private->ti);
+  err = current_pointers->td_thr_get_info_p (&thread_info->private->th,
+					     &thread_info->private->ti);
   if (err != TD_OK)
     error ("thread_db_get_info: cannot get thread info: %s",
 	   thread_db_err_str (err));
@@ -365,7 +376,8 @@ thread_from_lwp (ptid_t ptid)
 
   gdb_assert (is_lwp (ptid));
 
-  err = td_ta_map_lwp2thr_p (thread_agent, GET_LWP (ptid), &th);
+  err = current_pointers->td_ta_map_lwp2thr_p (thread_agent, GET_LWP (ptid),
+					       &th);
   if (err != TD_OK)
     error ("Cannot find user-level thread for LWP %ld: %s",
 	   GET_LWP (ptid), thread_db_err_str (err));
@@ -420,85 +432,102 @@ verbose_dlsym (void *handle, const char 
   return sym;
 }
 
-static int
-thread_db_load (void)
+static struct thread_db_pointers *
+thread_db_load (const char *name)
 {
+  struct thread_db_pointers *ptrs;
+  Dl_info info;
   void *handle;
   td_err_e err;
 
-  handle = dlopen (LIBTHREAD_DB_SO, RTLD_NOW);
+  ptrs = xcalloc (1, sizeof (struct thread_db_pointers));
+
+  handle = dlopen (name, RTLD_NOW);
   if (handle == NULL)
     {
-      fprintf_filtered (gdb_stderr, "\n\ndlopen failed on '%s' - %s\n",
-			LIBTHREAD_DB_SO, dlerror ());
-      fprintf_filtered (gdb_stderr,
-			"GDB will not be able to debug pthreads.\n\n");
+      if (all_pointers == NULL)
+	{
+	  fprintf_filtered (gdb_stderr, "\n\ndlopen failed on '%s' - %s\n",
+			    name, dlerror ());
+	  fprintf_filtered (gdb_stderr,
+			    "GDB will not be able to debug pthreads.\n\n");
+	}
       return 0;
     }
 
   /* Initialize pointers to the dynamic library functions we will use.
      Essential functions first.  */
 
-  td_init_p = verbose_dlsym (handle, "td_init");
-  if (td_init_p == NULL)
+  ptrs->td_init_p = verbose_dlsym (handle, "td_init");
+  if (ptrs->td_init_p == NULL)
     return 0;
 
-  td_ta_new_p = verbose_dlsym (handle, "td_ta_new");
-  if (td_ta_new_p == NULL)
+  ptrs->td_ta_new_p = verbose_dlsym (handle, "td_ta_new");
+  if (ptrs->td_ta_new_p == NULL)
     return 0;
 
-  td_ta_map_id2thr_p = verbose_dlsym (handle, "td_ta_map_id2thr");
-  if (td_ta_map_id2thr_p == NULL)
+  ptrs->td_ta_map_id2thr_p = verbose_dlsym (handle, "td_ta_map_id2thr");
+  if (ptrs->td_ta_map_id2thr_p == NULL)
     return 0;
 
-  td_ta_map_lwp2thr_p = verbose_dlsym (handle, "td_ta_map_lwp2thr");
-  if (td_ta_map_lwp2thr_p == NULL)
+  ptrs->td_ta_map_lwp2thr_p = verbose_dlsym (handle, "td_ta_map_lwp2thr");
+  if (ptrs->td_ta_map_lwp2thr_p == NULL)
     return 0;
 
-  td_ta_thr_iter_p = verbose_dlsym (handle, "td_ta_thr_iter");
-  if (td_ta_thr_iter_p == NULL)
+  ptrs->td_ta_thr_iter_p = verbose_dlsym (handle, "td_ta_thr_iter");
+  if (ptrs->td_ta_thr_iter_p == NULL)
     return 0;
 
-  td_thr_validate_p = verbose_dlsym (handle, "td_thr_validate");
-  if (td_thr_validate_p == NULL)
+  ptrs->td_thr_validate_p = verbose_dlsym (handle, "td_thr_validate");
+  if (ptrs->td_thr_validate_p == NULL)
     return 0;
 
-  td_thr_get_info_p = verbose_dlsym (handle, "td_thr_get_info");
-  if (td_thr_get_info_p == NULL)
+  ptrs->td_thr_get_info_p = verbose_dlsym (handle, "td_thr_get_info");
+  if (ptrs->td_thr_get_info_p == NULL)
     return 0;
 
-  td_thr_getfpregs_p = verbose_dlsym (handle, "td_thr_getfpregs");
-  if (td_thr_getfpregs_p == NULL)
+  ptrs->td_thr_getfpregs_p = verbose_dlsym (handle, "td_thr_getfpregs");
+  if (ptrs->td_thr_getfpregs_p == NULL)
     return 0;
 
-  td_thr_getgregs_p = verbose_dlsym (handle, "td_thr_getgregs");
-  if (td_thr_getgregs_p == NULL)
+  ptrs->td_thr_getgregs_p = verbose_dlsym (handle, "td_thr_getgregs");
+  if (ptrs->td_thr_getgregs_p == NULL)
     return 0;
 
-  td_thr_setfpregs_p = verbose_dlsym (handle, "td_thr_setfpregs");
-  if (td_thr_setfpregs_p == NULL)
+  ptrs->td_thr_setfpregs_p = verbose_dlsym (handle, "td_thr_setfpregs");
+  if (ptrs->td_thr_setfpregs_p == NULL)
     return 0;
 
-  td_thr_setgregs_p = verbose_dlsym (handle, "td_thr_setgregs");
-  if (td_thr_setgregs_p == NULL)
+  ptrs->td_thr_setgregs_p = verbose_dlsym (handle, "td_thr_setgregs");
+  if (ptrs->td_thr_setgregs_p == NULL)
     return 0;
 
   /* Initialize the library.  */
-  err = td_init_p ();
+  err = ptrs->td_init_p ();
   if (err != TD_OK)
     {
       warning ("Cannot initialize libthread_db: %s", thread_db_err_str (err));
+      xfree (ptrs);
       return 0;
     }
 
   /* These are not essential.  */
-  td_ta_event_addr_p = dlsym (handle, "td_ta_event_addr");
-  td_ta_set_event_p = dlsym (handle, "td_ta_set_event");
-  td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg");
-  td_thr_event_enable_p = dlsym (handle, "td_thr_event_enable");
-  td_thr_tls_get_addr_p = dlsym (handle, "td_thr_tls_get_addr");
+  ptrs->td_ta_event_addr_p = dlsym (handle, "td_ta_event_addr");
+  ptrs->td_ta_set_event_p = dlsym (handle, "td_ta_set_event");
+  ptrs->td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg");
+  ptrs->td_thr_event_enable_p = dlsym (handle, "td_thr_event_enable");
+  ptrs->td_thr_tls_get_addr_p = dlsym (handle, "td_thr_tls_get_addr");
+
+  if (dladdr (ptrs->td_ta_new_p, &info) != 0)
+    ptrs->filename = info.dli_fname;
+
+  /* Try dlinfo?  */
+
+  if (ptrs->filename == NULL)
+    /* Paranoid - don't let a NULL path slip through.  */
+    ptrs->filename = name;
 
-  return 1;
+  return ptrs;
 }
 
 static td_err_e
@@ -508,7 +537,7 @@ enable_thread_event (td_thragent_t *thre
   td_err_e err;
 
   /* Get the breakpoint address for thread EVENT.  */
-  err = td_ta_event_addr_p (thread_agent, event, &notify);
+  err = current_pointers->td_ta_event_addr_p (thread_agent, event, &notify);
   if (err != TD_OK)
     return err;
 
@@ -534,8 +563,10 @@ enable_thread_event_reporting (void)
 
   /* We cannot use the thread event reporting facility if these
      functions aren't available.  */
-  if (td_ta_event_addr_p == NULL || td_ta_set_event_p == NULL
-      || td_ta_event_getmsg_p == NULL || td_thr_event_enable_p == NULL)
+  if (current_pointers->td_ta_event_addr_p == NULL
+      || current_pointers->td_ta_set_event_p == NULL
+      || current_pointers->td_ta_event_getmsg_p == NULL
+      || current_pointers->td_thr_event_enable_p == NULL)
     return;
 
   /* Set the process wide mask saying which events we're interested in.  */
@@ -552,7 +583,7 @@ enable_thread_event_reporting (void)
 #endif
     td_event_addset (&events, TD_DEATH);
 
-  err = td_ta_set_event_p (thread_agent, &events);
+  err = current_pointers->td_ta_set_event_p (thread_agent, &events);
   if (err != TD_OK)
     {
       warning ("Unable to set global thread event mask: %s",
@@ -592,7 +623,7 @@ disable_thread_event_reporting (void)
   /* Set the process wide mask saying we aren't interested in any
      events anymore.  */
   td_event_emptyset (&events);
-  td_ta_set_event_p (thread_agent, &events);
+  current_pointers->td_ta_set_event_p (thread_agent, &events);
 
   /* Delete thread event breakpoints, if any.  */
   remove_thread_event_breakpoints ();
@@ -635,7 +666,6 @@ check_thread_signals (void)
 static void
 check_for_thread_db (void)
 {
-  td_err_e err;
   static int already_loaded;
 
   /* First time through, report that libthread_db was successfuly
@@ -644,19 +674,8 @@ check_for_thread_db (void)
 
   if (!already_loaded)
     {
-      Dl_info info;
-      const char *library = NULL;
-      if (dladdr ((*td_ta_new_p), &info) != 0)
-	library = info.dli_fname;
-
-      /* Try dlinfo?  */
-
-      if (library == NULL)
-	/* Paranoid - don't let a NULL path slip through.  */
-	library = LIBTHREAD_DB_SO;
-
       printf_unfiltered ("Using host libthread_db library \"%s\".\n",
-			 library);
+			 all_pointers->filename);
       already_loaded = 1;
     }
 
@@ -674,28 +693,34 @@ check_for_thread_db (void)
   proc_handle.pid = GET_PID (inferior_ptid);
 
   /* Now attempt to open a connection to the thread library.  */
-  err = td_ta_new_p (&proc_handle, &thread_agent);
-  switch (err)
+  for (current_pointers = all_pointers;
+       current_pointers != NULL;
+       current_pointers = current_pointers->next)
     {
-    case TD_NOLIBTHREAD:
-      /* No thread library was detected.  */
-      break;
-
-    case TD_OK:
-      printf_unfiltered ("[Thread debugging using libthread_db enabled]\n");
+      td_err_e err;
+      err = current_pointers->td_ta_new_p (&proc_handle, &thread_agent);
+      switch (err)
+	{
+	case TD_NOLIBTHREAD:
+	  /* No thread library was detected.  */
+	  break;
 
-      /* The thread library was detected.  Activate the thread_db target.  */
-      push_target (&thread_db_ops);
-      using_thread_db = 1;
+	case TD_OK:
+	  printf_unfiltered ("[Thread debugging using libthread_db enabled]\n");
 
-      enable_thread_event_reporting ();
-      thread_db_find_new_threads ();
-      break;
+	  /* The thread library was detected.  Activate the thread_db target.  */
+	  push_target (&thread_db_ops);
+	  using_thread_db = 1;
+
+	  enable_thread_event_reporting ();
+	  thread_db_find_new_threads ();
+	  return;
 
-    default:
-      warning ("Cannot initialize thread debugging library: %s",
-	       thread_db_err_str (err));
-      break;
+	default:
+	  warning ("Cannot initialize thread debugging library: %s",
+		   thread_db_err_str (err));
+	  break;
+	}
     }
 }
 
@@ -766,7 +791,7 @@ attach_thread (ptid_t ptid, const td_thr
 #endif
 
   /* Enable thread event reporting for this thread.  */
-  err = td_thr_event_enable_p (th_p, 1);
+  err = current_pointers->td_thr_event_enable_p (th_p, 1);
   if (err != TD_OK)
     error ("Cannot enable thread event reporting for %s: %s",
 	   target_pid_to_str (ptid), thread_db_err_str (err));
@@ -892,7 +917,7 @@ check_event (ptid_t ptid)
 
   do
     {
-      err = td_ta_event_getmsg_p (thread_agent, &msg);
+      err = current_pointers->td_ta_event_getmsg_p (thread_agent, &msg);
       if (err != TD_OK)
 	{
 	  if (err == TD_NOMSG)
@@ -902,7 +927,7 @@ check_event (ptid_t ptid)
 		 thread_db_err_str (err));
 	}
 
-      err = td_thr_get_info_p (msg.th_p, &ti);
+      err = current_pointers->td_thr_get_info_p (msg.th_p, &ti);
       if (err != TD_OK)
 	error ("Cannot get thread info: %s", thread_db_err_str (err));
 
@@ -1015,12 +1040,14 @@ thread_db_fetch_registers (int regno)
   thread_info = find_thread_pid (inferior_ptid);
   thread_db_map_id2thr (thread_info, 1);
 
-  err = td_thr_getgregs_p (&thread_info->private->th, gregset);
+  err = current_pointers->td_thr_getgregs_p (&thread_info->private->th,
+					     gregset);
   if (err != TD_OK)
     error ("Cannot fetch general-purpose registers for thread %ld: %s",
 	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
 
-  err = td_thr_getfpregs_p (&thread_info->private->th, &fpregset);
+  err = current_pointers->td_thr_getfpregs_p (&thread_info->private->th,
+					      &fpregset);
   if (err != TD_OK)
     error ("Cannot get floating-point registers for thread %ld: %s",
 	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
@@ -1062,11 +1089,13 @@ thread_db_store_registers (int regno)
   fill_gregset ((gdb_gregset_t *) gregset, -1);
   fill_fpregset (&fpregset, -1);
 
-  err = td_thr_setgregs_p (&thread_info->private->th, gregset);
+  err = current_pointers->td_thr_setgregs_p (&thread_info->private->th,
+					     gregset);
   if (err != TD_OK)
     error ("Cannot store general-purpose registers for thread %ld: %s",
 	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
-  err = td_thr_setfpregs_p (&thread_info->private->th, &fpregset);
+  err = current_pointers->td_thr_setfpregs_p (&thread_info->private->th,
+					      &fpregset);
   if (err != TD_OK)
     error ("Cannot store floating-point registers  for thread %ld: %s",
 	   (long) GET_THREAD (inferior_ptid), thread_db_err_str (err));
@@ -1136,15 +1165,14 @@ thread_db_thread_alive (ptid_t ptid)
       if (!thread_info->private->th_valid)
 	return 0;
 
-      err = td_thr_validate_p (&thread_info->private->th);
+      err = current_pointers->td_thr_validate_p (&thread_info->private->th);
       if (err != TD_OK)
 	return 0;
 
       if (!thread_info->private->ti_valid)
 	{
-	  err =
-	    td_thr_get_info_p (&thread_info->private->th,
-			       &thread_info->private->ti);
+	  err = current_pointers->td_thr_get_info_p
+	    (&thread_info->private->th, &thread_info->private->ti);
 	  if (err != TD_OK)
 	    return 0;
 	  thread_info->private->ti_valid = 1;
@@ -1170,7 +1198,7 @@ find_new_threads_callback (const td_thrh
   td_err_e err;
   ptid_t ptid;
 
-  err = td_thr_get_info_p (th_p, &ti);
+  err = current_pointers->td_thr_get_info_p (th_p, &ti);
   if (err != TD_OK)
     error ("find_new_threads_callback: cannot get thread info: %s",
 	   thread_db_err_str (err));
@@ -1192,9 +1220,10 @@ thread_db_find_new_threads (void)
   td_err_e err;
 
   /* Iterate over all user-space threads to discover new threads.  */
-  err = td_ta_thr_iter_p (thread_agent, find_new_threads_callback, NULL,
-			  TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
-			  TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+  err = current_pointers->td_ta_thr_iter_p
+    (thread_agent, find_new_threads_callback, NULL,
+     TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
+     TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
   if (err != TD_OK)
     error ("Cannot find new threads: %s", thread_db_err_str (err));
 }
@@ -1257,7 +1286,7 @@ thread_db_get_thread_local_address (ptid
       struct thread_info *thread_info;
 
       /* glibc doesn't provide the needed interface.  */
-      if (!td_thr_tls_get_addr_p)
+      if (!current_pointers->td_thr_tls_get_addr_p)
 	error ("Cannot find thread-local variables in this thread library.");
 
       /* Get the address of the link map for this objfile.  */
@@ -1279,8 +1308,8 @@ thread_db_get_thread_local_address (ptid
       thread_db_map_id2thr (thread_info, 1);
 
       /* Finally, get the address of the variable.  */
-      err = td_thr_tls_get_addr_p (&thread_info->private->th, (void *) lm,
-				   offset, &address);
+      err = current_pointers->td_thr_tls_get_addr_p
+	(&thread_info->private->th, (void *) lm, offset, &address);
 
 #ifdef THREAD_DB_HAS_TD_NOTALLOC
       /* The memory hasn't been allocated, yet.  */
@@ -1360,17 +1389,49 @@ init_thread_db_ops (void)
 void
 _initialize_thread_db (void)
 {
+  struct thread_db_pointers *ptrs;
+  const char *p;
+
   /* Only initialize the module if we can load libthread_db.  */
-  if (thread_db_load ())
-    {
-      init_thread_db_ops ();
-      add_target (&thread_db_ops);
+  ptrs = thread_db_load (LIBTHREAD_DB_SO);
+  if (ptrs == NULL)
+    return;
+
+  all_pointers = ptrs;
 
-      /* Add ourselves to objfile event chain.  */
-      target_new_objfile_chain = deprecated_target_new_objfile_hook;
-      deprecated_target_new_objfile_hook = thread_db_new_objfile;
+  /* Some GNU/Linux systems have more than one binary-compatible copy
+     of libthread_db.  If we can find a second one, load that too.
+     The inferior may force the use of a different threading package
+     than we expect.  Our guess for the location is somewhat hokey:
+     strip out anything between /lib (or /lib64) and LIBTHREAD_DB_SO.
+     If we loaded the NPTL libthread_db by default, this may find us
+     the LinuxThreads copy.  */
+  p = strrchr (ptrs->filename, '/');
+  while (p != NULL && p > ptrs->filename)
+    {
+      const char *component;
 
-      /* Register ourselves for the new inferior observer.  */
-      observer_attach_inferior_created (check_for_thread_db_observer);
+      component = memrchr (ptrs->filename, '/', p - ptrs->filename);
+      if (component != NULL && strncmp (component, "/lib", 4) == 0)
+	{
+	  char *new_name = xmalloc (p - ptrs->filename + 2
+				    + strlen (LIBTHREAD_DB_SO));
+	  memcpy (new_name, ptrs->filename, p - ptrs->filename + 1);
+	  strcpy (new_name + (p - ptrs->filename) + 1, LIBTHREAD_DB_SO);
+	  ptrs->next = thread_db_load (new_name);
+	  xfree (new_name);
+	  break;
+	}
+      p = component;
     }
+
+  init_thread_db_ops ();
+  add_target (&thread_db_ops);
+
+  /* Add ourselves to objfile event chain.  */
+  target_new_objfile_chain = deprecated_target_new_objfile_hook;
+  deprecated_target_new_objfile_hook = thread_db_new_objfile;
+
+  /* Register ourselves for the new inferior observer.  */
+  observer_attach_inferior_created (check_for_thread_db_observer);
 }
