18 files changed, 492 insertions, 226 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 155574d..020e21f 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,67 @@
+2009-07-02  Pedro Alves  <pedro@codesourcery.com>
+
+	* linux-nat.c (linux_child_follow_fork): If we're staying attached
+	to the child process, enable event reporting on it.  Don't handle
+	checkpoints here.  Instead, add the child fork to the lwp thread
+	and inferior lists without clobbering the previous inferior.  Let
+	the thread_db layer learn about a new child process, even if
+	following the parent.
+	(linux_nat_switch_fork): Delete lwps of the current inferior only,
+	instead of clearing the whole list.  Use thread_change_ptid to
+	give the core the illusion the new checkpoint is still the same
+	inferior.  Clear the register cache.
+	(linux_handle_extended_wait): Handle checkpoints here.
+	(linux_multi_process): Turn on.
+	* linux-fork.c (struct fork_info) <pc>: Remove field.
+	(init_fork_list): Do not delete the checkpoint from the inferior
+	list (it is not there).
+	(fork_load_infrun_state): Don't switch inferior_ptid here.  Pass
+	the new checkpoint's ptid to linux_nat_switch_fork.
+	(fork_save_infrun_state): Make static.  Don't stop the pc field of
+	fork_info, it's gone.
+	(linux_fork_mourn_inferior): Don't delete the checkpoint from the
+	inferior list, it's not there.
+	(linux_fork_detach): Ditto.
+	(delete_fork_command): Replace mention of fork/checkpoint by
+	checkpoint only.
+	(detach_fork_command): Likewise.  Don't delete the checkpoint from
+	the inferior list.
+	(info_forks_command): Adjust.
+	(restore_detach_fork): Delete.
+	(checkpointing_pid): New.
+	(linux_fork_checkpointing_p): New.
+	(save_detach_fork): Delete.
+	(checkpoint_command): Delete temp_detach_fork.  Don't remove
+	breakpoints, that's a nop.  Store the pid of the process we're
+	checkpointing, and use make_cleanup_restore_integer to restore it.
+	Don't reinsert breakpoints here.
+	(process_command, fork_command): Delete.
+	(restart_command): Update comments to only mention checkpoints,
+	not forks.
+	(_initialize_linux_fork): Delete "fork", "process", "info forks"
+	commands.
+	* linux-fork.h (fork_save_infrun_state, fork_list): Delete
+	declarations.
+	(linux_fork_checkpointing_p): Declare.
+	* cli/cli-cmds.c (killlist): New.
+	* cli/cli-cmds.h (killlist): Declare.
+	* gdbcmd.h (killlist): Declare.
+	* inferior.c: Include "gdbthread.h".
+	(detach_inferior_command, kill_inferior_command)
+	(inferior_command): New.
+	(info_inferiors_command): Allow specifying a specific inferior id.
+	(_initialize_inferiors): Register "inferior", "kill inferior" and
+	"detach inferior" commands.
+	* infcmd.c (_initialize_infcmd): Make "kill" a prefix command.
+	* gdbthread.h (any_thread_of_process): Declare.
+	* thread.c (any_thread_of_process): New.
+
+	* NEWS: Mention multi-inferior debugging.  Mention 'info
+	inferiors', 'inferior', 'detach inferior' and 'kill inferior' as
+	new commands.
+	(Removed commands): New section, mentioning that 'info forks',
+	'fork', 'process', 'delete fork' and 'detach fork' are now gone.
+
 2009-07-02  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* gdbarch.sh (current_gdbarch): Remove global variable.
diff --git a/gdb/NEWS b/gdb/NEWS
index b12c5dc..68776a5 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -175,6 +175,16 @@ GDB will now correctly handle all of:
 * Support for user-defined prefixed commands.  The "define" command can
 add new commands to existing prefixes, e.g. "target".
 
+* Multi-inferior, multi-process debugging.
+
+  GDB now has generalized support for multi-inferior debugging.  See
+  "Debugging Multiple Inferiors" in the manual for more information.
+  Although availability still depends on target support, the command
+  set is more uniform now.  The GNU/Linux specific multi-forks support
+  has been migrated to this new framework.  This implied some user
+  visible changes; see "New commands" and also "Removed commands"
+  below.
+
 * New commands (for set/show, see "New options" below)
 
 find [/size-char] [/max-count] start-address, end-address|+search-space-size,
@@ -197,6 +207,18 @@ macro undef
 info os processes
   Show operating system information about processes.
 
+info inferiors
+  List the inferiors currently under GDB's control.
+
+inferior NUM
+  Switch focus to inferior number NUM.
+
+detach inferior NUM
+  Detach from inferior number NUM.
+
+kill inferior NUM
+  Kill inferior number NUM.
+
 * New options
 
 set sh calling-convention
@@ -320,6 +342,36 @@ show schedule-multiple
   Allow GDB to resume all threads of all processes or only threads of
   the current process.
 
+* Removed commands
+
+info forks
+  For program forks, this is replaced by the new more generic `info
+  inferiors' command.  To list checkpoints, you can still use the
+  `info checkpoints' command, which was an alias for the `info forks'
+  command.
+
+fork NUM
+  Replaced by the new `inferior' command.  To switch between
+  checkpoints, you can still use the `restart' command, which was an
+  alias for the `fork' command.
+
+process PID
+  This is removed, since some targets don't have a notion of
+  processes.  To switch between processes, you can still use the
+  `inferior' command using GDB's own inferior number.
+
+delete fork NUM
+  For program forks, this is replaced by the new more generic `kill
+  inferior' command.  To delete a checkpoint, you can still use the
+  `delete checkpoint' command, which was an alias for the `delete
+  fork' command.
+
+detach fork NUM
+  For program forks, this is replaced by the new more generic `detach
+  inferior' command.  To detach a checkpoint, you can still use the
+  `detach checkpoint' command, which was an alias for the `detach
+  fork' command.
+
 * New native configurations
 
 x86/x86_64 Darwin		i[34567]86-*-darwin*
diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 37b027b..1b17751 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -125,6 +125,10 @@ struct cmd_list_element *deletelist;
 
 struct cmd_list_element *detachlist;
 
+/* Chain containing all defined kill subcommands. */
+
+struct cmd_list_element *killlist;
+
 /* Chain containing all defined "enable breakpoint" subcommands. */
 
 struct cmd_list_element *enablebreaklist;
diff --git a/gdb/cli/cli-cmds.h b/gdb/cli/cli-cmds.h
index 5b08936..3260fe8 100644
--- a/gdb/cli/cli-cmds.h
+++ b/gdb/cli/cli-cmds.h
@@ -41,6 +41,10 @@ extern struct cmd_list_element *deletelist;
 
 extern struct cmd_list_element *detachlist;
 
+/* Chain containing all defined kill subcommands.  */
+
+extern struct cmd_list_element *killlist;
+
 /* Chain containing all defined toggle subcommands. */
 
 extern struct cmd_list_element *togglelist;
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index f5d4950..2ed8cc8 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,12 @@
+2009-07-02  Pedro Alves  <pedro@codesourcery.com>
+
+	* gdb.texinfo (Debugging multiple inferiors): Document the
+	"inferior", "detach inferior" and "kill inferior" commands.
+	(Debugging Programs with Multiple Processes): Adjust to mention
+	generic "inferior" commands.  Delete mention of "detach fork" and
+	"delete fork".  Cross reference to "Debugging multiple inferiors"
+	section.
+
 2009-07-02  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* gdbint.texinfo (Item Output Functions): Update signature
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 272e807..d1ce3e1 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -2374,7 +2374,39 @@ To find out what inferiors exist at any moment, use @code{info inferiors}:
 @kindex info inferiors
 @item info inferiors
 Print a list of all inferiors currently being managed by @value{GDBN}.
+@end table
+
+To switch focus between inferiors, use the @code{inferior} command:
+
+@table @code
+@kindex inferior @var{inferior-id}
+@item inferior @var{inferior-id}
+Make inferior number @var{inferior-id} the current inferior.  The
+argument @var{inferior-id} is the internal inferior number assigned by
+@value{GDBN}, as shown in the first field of the @samp{info inferiors}
+display.
+@end table
+
+To quit debugging one of the inferiors, you can either detach from it
+by using the @w{@code{detach inferior}} command (allowing it to run
+independently), or kill it using the @w{@code{kill inferior}} command:
 
+@table @code
+@kindex detach inferior @var{inferior-id}
+@item detach inferior @var{inferior-id}
+Detach from the inferior identified by @value{GDBN} inferior number
+@var{inferior-id}, and remove it from the inferior list.
+
+@kindex kill inferior @var{inferior-id}
+@item kill inferior @var{inferior-id}
+Kill the inferior identified by @value{GDBN} inferior number
+@var{inferior-id}, and remove it from the inferior list.
+@end table
+
+To be notified when inferiors are started or exit under @value{GDBN}'s
+control use @w{@code{set print inferior-events}}:
+
+@table @code
 @kindex set print inferior-events
 @cindex print messages on inferior start and exit
 @item set print inferior-events
@@ -2758,51 +2790,17 @@ is held suspended.
 Show whether detach-on-fork mode is on/off.
 @end table
 
-If you choose to set @samp{detach-on-fork} mode off, then
-@value{GDBN} will retain control of all forked processes (including
-nested forks).  You can list the forked processes under the control of
-@value{GDBN} by using the @w{@code{info forks}} command, and switch
-from one fork to another by using the @w{@code{fork}} command.
-
-@table @code
-@kindex info forks
-@item info forks
-Print a list of all forked processes under the control of @value{GDBN}.
-The listing will include a fork id, a process id, and the current 
-position (program counter) of the process.
-
-@kindex fork @var{fork-id}
-@item fork @var{fork-id}
-Make fork number @var{fork-id} the current process.  The argument
-@var{fork-id} is the internal fork number assigned by @value{GDBN},
-as shown in the first field of the @samp{info forks} display.
-
-@kindex process @var{process-id}
-@item process @var{process-id}
-Make process number @var{process-id} the current process.  The
-argument @var{process-id} must be one that is listed in the output of
-@samp{info forks}.
-
-@end table
+If you choose to set @samp{detach-on-fork} mode off, then @value{GDBN}
+will retain control of all forked processes (including nested forks).
+You can list the forked processes under the control of @value{GDBN} by
+using the @w{@code{info inferiors}} command, and switch from one fork
+to another by using the @code{inferior} command (@pxref{Inferiors,
+,Debugging Multiple Inferiors}).
 
 To quit debugging one of the forked processes, you can either detach
-from it by using the @w{@code{detach fork}} command (allowing it to
-run independently), or delete (and kill) it using the
-@w{@code{delete fork}} command.
-
-@table @code
-@kindex detach fork @var{fork-id}
-@item detach fork @var{fork-id}
-Detach from the process identified by @value{GDBN} fork number
-@var{fork-id}, and remove it from the fork list.  The process will be
-allowed to run independently.
-
-@kindex delete fork @var{fork-id}
-@item delete fork @var{fork-id}
-Kill the process identified by @value{GDBN} fork number @var{fork-id},
-and remove it from the fork list.
-
-@end table
+from it by using the @w{@code{detach inferior}} command (allowing it
+to run independently), or kill it using the @w{@code{kill inferior}}
+command.  @xref{Inferiors, ,Debugging Multiple Inferiors}.
 
 If you ask to debug a child process and a @code{vfork} is followed by an
 @code{exec}, @value{GDBN} executes the new target up to the first
@@ -2810,8 +2808,8 @@ breakpoint in the new target.  If you have a breakpoint set on
 @code{main} in your original program, the breakpoint will also be set on
 the child process's @code{main}.
 
-When a child process is spawned by @code{vfork}, you cannot debug the
-child or parent until an @code{exec} call completes.
+On some systems, when a child process is spawned by @code{vfork}, you
+cannot debug the child or parent until an @code{exec} call completes.
 
 If you issue a @code{run} command to @value{GDBN} after an @code{exec}
 call executes, the new target restarts.  To restart the parent process,
diff --git a/gdb/gdbcmd.h b/gdb/gdbcmd.h
index 57a06ed..0075fc1 100644
--- a/gdb/gdbcmd.h
+++ b/gdb/gdbcmd.h
@@ -52,6 +52,10 @@ extern struct cmd_list_element *deletelist;
 
 extern struct cmd_list_element *detachlist;
 
+/* Chain containing all defined kill subcommands.  */
+
+extern struct cmd_list_element *killlist;
+
 /* Chain containing all defined toggle subcommands.  */
 
 extern struct cmd_list_element *togglelist;
diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index 956ef9a..79d33fe 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -243,6 +243,9 @@ struct thread_info *find_thread_id (int num);
    returns the first thread in the list.  */
 struct thread_info *first_thread_of_process (int pid);
 
+/* Returns any thread of process PID.  */
+extern struct thread_info *any_thread_of_process (int pid);
+
 /* Change the ptid of thread OLD_PTID to NEW_PTID.  */
 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
 
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 28b618f..9e98290 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -2698,8 +2698,9 @@ fully linked executable files and separately compiled object files as needed."),
 	       &showlist);
   set_cmd_completer (c, noop_completer);
 
-  add_com ("kill", class_run, kill_command,
-	   _("Kill execution of program being debugged."));
+  add_prefix_cmd ("kill", class_run, kill_command,
+		  _("Kill execution of program being debugged."),
+		  &killlist, "kill ", 0, &cmdlist);
 
   add_com ("attach", class_run, attach_command, _("\
 Attach to a process or file outside of GDB.\n\
diff --git a/gdb/inferior.c b/gdb/inferior.c
index a99a3be..43eacda 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -25,6 +25,7 @@
 #include "gdbthread.h"
 #include "ui-out.h"
 #include "observer.h"
+#include "gdbthread.h"
 
 void _initialize_inferiors (void);
 
@@ -352,12 +353,112 @@ print_inferior (struct ui_out *uiout, int requested_inferior)
   do_cleanups (old_chain);
 }
 
+static void
+detach_inferior_command (char *args, int from_tty)
+{
+  int num, pid;
+  struct thread_info *tp;
+
+  if (!args || !*args)
+    error (_("Requires argument (inferior id to detach)"));
+
+  num = parse_and_eval_long (args);
+
+  if (!valid_gdb_inferior_id (num))
+    error (_("Inferior ID %d not known."), num);
+
+  pid = gdb_inferior_id_to_pid (num);
+
+  tp = any_thread_of_process (pid);
+  if (!tp)
+    error (_("Inferior has no threads."));
+
+  switch_to_thread (tp->ptid);
+
+  detach_command (NULL, from_tty);
+}
+
+static void
+kill_inferior_command (char *args, int from_tty)
+{
+  int num, pid;
+  struct thread_info *tp;
+
+  if (!args || !*args)
+    error (_("Requires argument (inferior id to kill)"));
+
+  num = parse_and_eval_long (args);
+
+  if (!valid_gdb_inferior_id (num))
+    error (_("Inferior ID %d not known."), num);
+
+  pid = gdb_inferior_id_to_pid (num);
+
+  tp = any_thread_of_process (pid);
+  if (!tp)
+    error (_("Inferior has no threads."));
+
+  switch_to_thread (tp->ptid);
+
+  target_kill ();
+
+  bfd_cache_close_all ();
+}
+
+static void
+inferior_command (char *args, int from_tty)
+{
+  int num, pid;
+
+  if (!have_inferiors ())
+    error (_("No inferiors"));
+
+  num = parse_and_eval_long (args);
+
+  if (!valid_gdb_inferior_id (num))
+    error (_("Inferior ID %d not known."), num);
+
+  pid = gdb_inferior_id_to_pid (num);
+
+  if (pid != ptid_get_pid (inferior_ptid))
+    {
+      struct thread_info *tp;
+
+      tp = any_thread_of_process (pid);
+      if (!tp)
+	error (_("Inferior has no threads."));
+
+      switch_to_thread (tp->ptid);
+    }
+
+  printf_filtered (_("[Switching to thread %d (%s)] "),
+		   pid_to_thread_id (inferior_ptid),
+		   target_pid_to_str (inferior_ptid));
+
+  if (is_running (inferior_ptid))
+    ui_out_text (uiout, "(running)\n");
+  else
+    {
+      ui_out_text (uiout, "\n");
+      print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
+    }
+}
+
 /* Print information about currently known inferiors.  */
 
 static void
-info_inferiors_command (char *arg, int from_tty)
+info_inferiors_command (char *args, int from_tty)
 {
-  print_inferior (uiout, -1);
+  int requested = -1;
+
+  if (args && *args)
+    {
+      requested = parse_and_eval_long (args);
+      if (!valid_gdb_inferior_id (requested))
+	error (_("Inferior ID %d not known."), requested);
+    }
+
+  print_inferior (uiout, requested);
 }
 
 /* Print notices when new inferiors are created and die.  */
@@ -381,4 +482,17 @@ Show printing of inferior events (e.g., inferior start and exit)."), NULL,
          NULL,
          show_print_inferior_events,
          &setprintlist, &showprintlist);
+
+  add_cmd ("inferior", class_run, detach_inferior_command, _("\
+Detach from inferior ID."),
+	   &detachlist);
+
+  add_cmd ("inferior", class_run, kill_inferior_command, _("\
+Kill inferior ID."),
+	   &killlist);
+
+  add_cmd ("inferior", class_run, inferior_command, _("\
+Use this command to switch between inferiors.\n\
+The new inferior ID must be currently known."),
+	   &cmdlist);
 }
diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index b89e8b5..c0004d1 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -53,7 +53,6 @@ struct fork_info
   struct regcache *savedregs;	/* Convenient for info fork, saves 
 				   having to actually switch contexts.  */
   int clobber_regs;		/* True if we should restore saved regs.  */
-  ULONGEST pc;			/* PC for info fork.  */
   off_t *filepos;		/* Set of open file descriptors' offsets.  */
   int maxfd;
 };
@@ -211,7 +210,6 @@ init_fork_list (void)
   for (fp = fork_list; fp; fp = fpnext)
     {
       fpnext = fp->next;
-      delete_inferior (ptid_get_pid (fp->ptid));
       free_fork (fp);
     }
 
@@ -241,9 +239,7 @@ fork_load_infrun_state (struct fork_info *fp)
   extern void nullify_last_target_wait_ptid ();
   int i;
 
-  inferior_ptid = fp->ptid;
-
-  linux_nat_switch_fork (inferior_ptid);
+  linux_nat_switch_fork (fp->ptid);
 
   if (fp->savedregs && fp->clobber_regs)
     regcache_cpy (get_current_regcache (), fp->savedregs);
@@ -269,7 +265,7 @@ fork_load_infrun_state (struct fork_info *fp)
 /* Save infrun state for the fork PTID.
    Exported for use by linux child_follow_fork.  */
 
-extern void
+static void
 fork_save_infrun_state (struct fork_info *fp, int clobber_regs)
 {
   char path[MAXPATHLEN];
@@ -281,7 +277,6 @@ fork_save_infrun_state (struct fork_info *fp, int clobber_regs)
 
   fp->savedregs = regcache_dup (get_current_regcache ());
   fp->clobber_regs = clobber_regs;
-  fp->pc = regcache_read_pc (get_current_regcache ());
 
   if (clobber_regs)
     {
@@ -371,8 +366,6 @@ linux_fork_mourn_inferior (void)
      We need to delete that one from the fork_list, and switch
      to the next available fork.  */
   delete_fork (inferior_ptid);
-  /* Delete process from GDB's inferior list.  */
-  delete_inferior (ptid_get_pid (inferior_ptid));
 
   /* There should still be a fork - if there's only one left,
      delete_fork won't remove it, because we haven't updated
@@ -403,8 +396,6 @@ linux_fork_detach (char *args, int from_tty)
     error (_("Unable to detach %s"), target_pid_to_str (inferior_ptid));
 
   delete_fork (inferior_ptid);
-  /* Delete process from GDB's inferior list.  */
-  delete_inferior (ptid_get_pid (inferior_ptid));
 
   /* There should still be a fork - if there's only one left,
      delete_fork won't remove it, because we haven't updated
@@ -430,14 +421,14 @@ delete_fork_command (char *args, int from_tty)
   ptid_t ptid;
 
   if (!args || !*args)
-    error (_("Requires argument (fork/checkpoint id to delete)"));
+    error (_("Requires argument (checkpoint id to delete)"));
 
   ptid = fork_id_to_ptid (parse_and_eval_long (args));
   if (ptid_equal (ptid, minus_one_ptid))
-    error (_("No such fork/checkpoint id, %s"), args);
+    error (_("No such checkpoint id, %s"), args);
 
   if (ptid_equal (ptid, inferior_ptid))
-    error (_("Please switch to another fork/checkpoint before deleting the current one"));
+    error (_("Please switch to another checkpoint before deleting the current one"));
 
   if (ptrace (PTRACE_KILL, PIDGET (ptid), 0, 0))
     error (_("Unable to kill pid %s"), target_pid_to_str (ptid));
@@ -446,8 +437,6 @@ delete_fork_command (char *args, int from_tty)
     printf_filtered (_("Killed %s\n"), target_pid_to_str (ptid));
 
   delete_fork (ptid);
-  /* Delete process from GDB's inferior list.  */
-  delete_inferior (ptid_get_pid (ptid));
 }
 
 static void
@@ -456,14 +445,15 @@ detach_fork_command (char *args, int from_tty)
   ptid_t ptid;
 
   if (!args || !*args)
-    error (_("Requires argument (fork id to detach)"));
+    error (_("Requires argument (checkpoint id to detach)"));
 
   ptid = fork_id_to_ptid (parse_and_eval_long (args));
   if (ptid_equal (ptid, minus_one_ptid))
-    error (_("No such fork id, %s"), args);
+    error (_("No such checkpoint id, %s"), args);
 
   if (ptid_equal (ptid, inferior_ptid))
-    error (_("Please switch to another fork before detaching the current one"));
+    error (_("\
+Please switch to another checkpoint before detaching the current one"));
 
   if (ptrace (PTRACE_DETACH, PIDGET (ptid), 0, 0))
     error (_("Unable to detach %s"), target_pid_to_str (ptid));
@@ -472,8 +462,6 @@ detach_fork_command (char *args, int from_tty)
     printf_filtered (_("Detached %s\n"), target_pid_to_str (ptid));
 
   delete_fork (ptid);
-  /* Delete process from GDB's process table.  */
-  detach_inferior (ptid_get_pid (ptid));
 }
 
 /* Print information about currently known forks.  */
@@ -508,7 +496,7 @@ info_forks_command (char *arg, int from_tty)
       else
 	{
 	  printf_filtered ("  ");
-	  pc = fp->pc;
+	  pc = regcache_read_pc (fp->savedregs);
 	}
       printf_filtered ("%d %s", fp->num, target_pid_to_str (fp->ptid));
       if (fp->num == 0)
@@ -542,31 +530,19 @@ info_forks_command (char *arg, int from_tty)
   if (printed == NULL)
     {
       if (requested > 0)
-	printf_filtered (_("No fork number %d.\n"), requested);
+	printf_filtered (_("No checkpoint number %d.\n"), requested);
       else
-	printf_filtered (_("No forks.\n"));
+	printf_filtered (_("No checkpoints.\n"));
     }
 }
 
-/* Save/restore mode variable 'detach_fork':
-   We need to temporarily take over this mode variable, while
-   preserving the user-specified state, and make sure that it 
-   gets restored in case of error.
-
-   The int pointer that we use comes from the caller, so we can
-   be called more than once (even though currently we don't need to).  */
-
-static void 
-restore_detach_fork (void *arg)
-{
-  detach_fork = *(int *) arg;
-}
+/* The PID of the process we're checkpointing.  */
+static int checkpointing_pid = 0;
 
-static struct cleanup *
-save_detach_fork (int *saved_val)
+int
+linux_fork_checkpointing_p (int pid)
 {
-  *saved_val = detach_fork;
-  return make_cleanup (restore_detach_fork, (void *) saved_val);
+  return (checkpointing_pid == pid);
 }
 
 static void
@@ -581,12 +557,6 @@ checkpoint_command (char *args, int from_tty)
   pid_t retpid;
   struct cleanup *old_chain;
   long i;
-  /* Make this temp var static, 'cause it's used in the error context.  */
-  static int temp_detach_fork;
-
-  /* Remove breakpoints, so that they are not inserted
-     in the forked process.  */
-  remove_breakpoints ();
 
   /* Make the inferior fork, record its (and gdb's) state.  */
 
@@ -600,8 +570,11 @@ checkpoint_command (char *args, int from_tty)
 
   gdbarch = get_objfile_arch (fork_objf);
   ret = value_from_longest (builtin_type (gdbarch)->builtin_int, 0);
-  old_chain = save_detach_fork (&temp_detach_fork);
-  detach_fork = 0;
+
+  /* Tell linux-nat.c that we're checkpointing this inferior.  */
+  old_chain = make_cleanup_restore_integer (&checkpointing_pid);
+  checkpointing_pid = PIDGET (inferior_ptid);
+
   ret = call_function_by_hand (fork_fn, 0, &ret);
   do_cleanups (old_chain);
   if (!ret)	/* Probably can't happen.  */
@@ -629,7 +602,6 @@ checkpoint_command (char *args, int from_tty)
   if (!fp)
     error (_("Failed to find new fork"));
   fork_save_infrun_state (fp, 1);
-  insert_breakpoints ();
 }
 
 static void
@@ -656,37 +628,7 @@ linux_fork_context (struct fork_info *newfp, int from_tty)
   print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
 }
 
-/* Switch inferior process (fork) context, by process id.  */
-static void
-process_command (char *args, int from_tty)
-{
-  struct fork_info *fp;
-
-  if (!args || !*args)
-    error (_("Requires argument (process id to switch to)"));
-
-  if ((fp = find_fork_pid (parse_and_eval_long (args))) == NULL)
-    error (_("Not found: process id %s"), args);
-
-  linux_fork_context (fp, from_tty);
-}
-
-/* Switch inferior process (fork) context, by fork id.  */
-static void
-fork_command (char *args, int from_tty)
-{
-  struct fork_info *fp;
-
-  if (!args || !*args)
-    error (_("Requires argument (fork id to switch to)"));
-
-  if ((fp = find_fork_id (parse_and_eval_long (args))) == NULL)
-    error (_("Not found: fork id %s"), args);
-
-  linux_fork_context (fp, from_tty);
-}
-
-/* Switch inferior process (fork) context, by checkpoint id.  */
+/* Switch inferior process (checkpoint) context, by checkpoint id.  */
 static void
 restart_command (char *args, int from_tty)
 {
@@ -727,9 +669,8 @@ Tells gdb whether to detach the child of a fork."),
   add_com ("checkpoint", class_obscure, checkpoint_command, _("\
 Fork a duplicate process (experimental)."));
 
-  /* Restart command: restore the context of a specified fork
-     process.  May be used for "program forks" as well as for
-     "debugger forks" (checkpoints).  */
+  /* Restart command: restore the context of a specified checkpoint
+     process.  */
 
   add_com ("restart", class_obscure, restart_command, _("\
 restart <n>: restore program context from a checkpoint.\n\
@@ -739,36 +680,19 @@ Argument 'n' is checkpoint ID, as displayed by 'info checkpoints'."));
      fork list.  */
 
   add_cmd ("checkpoint", class_obscure, delete_fork_command, _("\
-Delete a fork/checkpoint (experimental)."),
+Delete a checkpoint (experimental)."),
 	   &deletelist);
 
   /* Detach checkpoint command: release the process to run independently, 
      and remove it from the fork list.  */
 
   add_cmd ("checkpoint", class_obscure, detach_fork_command, _("\
-Detach from a fork/checkpoint (experimental)."),
+Detach from a checkpoint (experimental)."),
 	   &detachlist);
 
   /* Info checkpoints command: list all forks/checkpoints 
      currently under gdb's control.  */
 
   add_info ("checkpoints", info_forks_command,
-	    _("IDs of currently known forks/checkpoints."));
-
-  /* Command aliases (let "fork" and "checkpoint" be used 
-     interchangeably).  */
-
-  add_alias_cmd ("fork", "checkpoint", class_obscure, 1, &deletelist);
-  add_alias_cmd ("fork", "checkpoint", class_obscure, 1, &detachlist);
-  add_info_alias ("forks", "checkpoints", 0);
-
-  /* "fork <n>" (by analogy to "thread <n>").  */
-  add_com ("fork", class_obscure, fork_command, _("\
-fork <n>: Switch between forked processes.\n\
-Argument 'n' is fork ID, as displayed by 'info forks'."));
-
-  /* "process <proc id>" as opposed to "fork <fork id>".  */
-  add_com ("process", class_obscure, process_command, _("\
-process <pid>: Switch between forked processes.\n\
-Argument 'pid' is process ID, as displayed by 'info forks' or 'shell ps'."));
+	    _("IDs of currently known checkpoints."));
 }
diff --git a/gdb/linux-fork.h b/gdb/linux-fork.h
index 0e7d1b6..23e9919 100644
--- a/gdb/linux-fork.h
+++ b/gdb/linux-fork.h
@@ -20,13 +20,11 @@
 struct fork_info;
 extern struct fork_info *add_fork (pid_t);
 extern struct fork_info *find_fork_pid (pid_t);
-extern void fork_save_infrun_state (struct fork_info *, int);
 extern void linux_fork_killall (void);
 extern void linux_fork_mourn_inferior (void);
 extern void linux_fork_detach (char *, int);
-extern int  forks_exist_p (void);
-
-struct fork_info *fork_list;
+extern int forks_exist_p (void);
+extern int linux_fork_checkpointing_p (int);
 
 extern int detach_fork;
 
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 0253fe9..f8d7a5c 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -338,6 +338,12 @@ static int stop_callback (struct lwp_info *lp, void *data);
 
 static void block_child_signals (sigset_t *prev_mask);
 static void restore_child_signals_mask (sigset_t *prev_mask);
+
+struct lwp_info;
+static struct lwp_info *add_lwp (ptid_t ptid);
+static void purge_lwp_list (int pid);
+static struct lwp_info *find_lwp_pid (ptid_t ptid);
+
 
 /* Trivial list manipulation functions to keep track of a list of
    new stopped processes.  */
@@ -587,6 +593,9 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child)
     parent_pid = ptid_get_pid (inferior_ptid);
   child_pid = PIDGET (inferior_thread ()->pending_follow.value.related_pid);
 
+  if (!detach_fork)
+    linux_enable_event_reporting (pid_to_ptid (child_pid));
+
   if (! follow_child)
     {
       /* We're already attached to the parent, by default. */
@@ -617,8 +626,9 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child)
 	}
       else
 	{
-	  struct fork_info *fp;
 	  struct inferior *parent_inf, *child_inf;
+	  struct lwp_info *lp;
+	  struct cleanup *old_chain;
 
 	  /* Add process to GDB's tables.  */
 	  child_inf = add_inferior (child_pid);
@@ -627,11 +637,16 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child)
 	  child_inf->attach_flag = parent_inf->attach_flag;
 	  copy_terminal_info (child_inf, parent_inf);
 
-	  /* Retain child fork in ptrace (stopped) state.  */
-	  fp = find_fork_pid (child_pid);
-	  if (!fp)
-	    fp = add_fork (child_pid);
-	  fork_save_infrun_state (fp, 0);
+	  old_chain = save_inferior_ptid ();
+
+	  inferior_ptid = ptid_build (child_pid, child_pid, 0);
+	  add_thread (inferior_ptid);
+	  lp = add_lwp (inferior_ptid);
+	  lp->stopped = 1;
+
+	  check_for_thread_db ();
+
+	  do_cleanups (old_chain);
 	}
 
       if (has_vforked)
@@ -692,6 +707,7 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child)
     {
       struct thread_info *tp;
       struct inferior *parent_inf, *child_inf;
+      struct lwp_info *lp;
 
       /* Before detaching from the parent, remove all breakpoints from it. */
       remove_breakpoints ();
@@ -733,30 +749,33 @@ linux_child_follow_fork (struct target_ops *ops, int follow_child)
 
       if (has_vforked)
 	{
+	  struct lwp_info *parent_lwp;
+
 	  linux_parent_pid = parent_pid;
+
+	  /* Get rid of the inferior on the core side as well.  */
+	  inferior_ptid = null_ptid;
 	  detach_inferior (parent_pid);
-	}
-      else if (!detach_fork)
-	{
-	  struct fork_info *fp;
-	  /* Retain parent fork in ptrace (stopped) state.  */
-	  fp = find_fork_pid (parent_pid);
-	  if (!fp)
-	    fp = add_fork (parent_pid);
-	  fork_save_infrun_state (fp, 0);
 
-	  /* Also add an entry for the child fork.  */
-	  fp = find_fork_pid (child_pid);
-	  if (!fp)
-	    fp = add_fork (child_pid);
-	  fork_save_infrun_state (fp, 0);
+	  /* Also get rid of all its lwps.  We will detach from this
+	     inferior soon-ish, but, we will still get an exit event
+	     reported through waitpid when it exits.  If we didn't get
+	     rid of the lwps from our list, we would end up reporting
+	     the inferior exit to the core, which would then try to
+	     mourn a non-existing (from the core's perspective)
+	     inferior.  */
+	  parent_lwp = find_lwp_pid (pid_to_ptid (parent_pid));
+	  purge_lwp_list (GET_PID (parent_lwp->ptid));
+	  linux_parent_pid = parent_pid;
 	}
-      else
+      else if (detach_fork)
 	target_detach (NULL, 0);
 
       inferior_ptid = ptid_build (child_pid, child_pid, 0);
+      add_thread (inferior_ptid);
+      lp = add_lwp (inferior_ptid);
+      lp->stopped = 1;
 
-      linux_nat_switch_fork (inferior_ptid);
       check_for_thread_db ();
     }
 
@@ -1073,22 +1092,30 @@ iterate_over_lwps (ptid_t filter,
   return NULL;
 }
 
-/* Update our internal state when changing from one fork (checkpoint,
-   et cetera) to another indicated by NEW_PTID.  We can only switch
-   single-threaded applications, so we only create one new LWP, and
-   the previous list is discarded.  */
+/* Update our internal state when changing from one checkpoint to
+   another indicated by NEW_PTID.  We can only switch single-threaded
+   applications, so we only create one new LWP, and the previous list
+   is discarded.  */
 
 void
 linux_nat_switch_fork (ptid_t new_ptid)
 {
   struct lwp_info *lp;
 
-  init_lwp_list ();
+  purge_lwp_list (GET_PID (inferior_ptid));
+
   lp = add_lwp (new_ptid);
   lp->stopped = 1;
 
-  init_thread_list ();
-  add_thread_silent (new_ptid);
+  /* This changes the thread's ptid while preserving the gdb thread
+     num.  Also changes the inferior pid, while preserving the
+     inferior num.  */
+  thread_change_ptid (inferior_ptid, new_ptid);
+
+  /* We've just told GDB core that the thread changed target id, but,
+     in fact, it really is a different thread, with different register
+     contents.  */
+  registers_changed ();
 }
 
 /* Handle the exit of a single thread LP.  */
@@ -1815,6 +1842,34 @@ linux_handle_extended_wait (struct lwp_info *lp, int status,
 
       ourstatus->value.related_pid = ptid_build (new_pid, new_pid, 0);
 
+      if (event == PTRACE_EVENT_FORK
+	  && linux_fork_checkpointing_p (GET_PID (lp->ptid)))
+	{
+	  struct fork_info *fp;
+
+	  /* Handle checkpointing by linux-fork.c here as a special
+	     case.  We don't want the follow-fork-mode or 'catch fork'
+	     to interfere with this.  */
+
+	  /* This won't actually modify the breakpoint list, but will
+	     physically remove the breakpoints from the child.  */
+	  detach_breakpoints (new_pid);
+
+	  /* Retain child fork in ptrace (stopped) state.  */
+	  fp = find_fork_pid (new_pid);
+	  if (!fp)
+	    fp = add_fork (new_pid);
+
+	  /* Report as spurious, so that infrun doesn't want to follow
+	     this fork.  We're actually doing an infcall in
+	     linux-fork.c.  */
+	  ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
+	  linux_enable_event_reporting (pid_to_ptid (new_pid));
+
+	  /* Report the stop to the core.  */
+	  return 0;
+	}
+
       if (event == PTRACE_EVENT_FORK)
 	ourstatus->kind = TARGET_WAITKIND_FORKED;
       else if (event == PTRACE_EVENT_VFORK)
@@ -4295,7 +4350,7 @@ linux_nat_supports_non_stop (void)
 /* True if we want to support multi-process.  To be removed when GDB
    supports multi-exec.  */
 
-int linux_multi_process = 0;
+int linux_multi_process = 1;
 
 static int
 linux_nat_supports_multi_process (void)
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index ca40ca3..2d28df1 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,13 @@
+2009-07-02  Pedro Alves  <pedro@codesourcery.com>
+
+	* gdb.base/multi-forks.exp: Only run detach-on-fork tests on
+	linux.  Adjust to use "inferior", "info inferiors", "detach
+	inferior" and "kill inferior" instead of "restart", "info fork",
+	"detach fork" and "delete fork".
+	* gdb.base/ending-run.exp: Spell out "info".
+	* gdb.base/help.exp: Adjust to use test_prefix_command_help for
+	the "kill" command.
+
 2009-07-02  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
 
 	* gdb.threads/tls-shared.exp: Update to locexpr_describe_location
diff --git a/gdb/testsuite/gdb.base/ending-run.exp b/gdb/testsuite/gdb.base/ending-run.exp
index cf33602..bc97e37 100644
--- a/gdb/testsuite/gdb.base/ending-run.exp
+++ b/gdb/testsuite/gdb.base/ending-run.exp
@@ -71,7 +71,7 @@ gdb_test "b ending-run.c:14" ".*Note.*also.*Breakpoint.*5.*" "b ending-run.c:14,
 gdb_test "cle ending-run.c:14" \
 	".*Deleted breakpoint 5.*" "Cleared 2 by line"
 
-send_gdb "inf line ending-run.c:14\n"
+send_gdb "info line ending-run.c:14\n"
 gdb_expect {
     -re ".*address (0x\[0-9a-fA-F]*).*$gdb_prompt $" {
         set line_nine $expect_out(1,string)
diff --git a/gdb/testsuite/gdb.base/help.exp b/gdb/testsuite/gdb.base/help.exp
index 4618a2c..5647101 100644
--- a/gdb/testsuite/gdb.base/help.exp
+++ b/gdb/testsuite/gdb.base/help.exp
@@ -300,7 +300,9 @@ gdb_test "help inspect" "Same as \"print\" command, except that if you are runni
 # test help jump
 gdb_test "help jump" "Continue program being debugged at specified line or address\.\[\r\n\]+Give as argument either LINENUM or \[*\]+ADDR, where ADDR is an expression\[\r\n\]+for an address to start at\." "help jump"
 # test help kill
-gdb_test "help kill" "Kill execution of program being debugged\." "help kill"
+test_prefix_command_help "kill" {
+    "Kill execution of program being debugged\.\[\r\n\]+"
+}
 # test help list "l" abbreviation
 gdb_test "help l" "List specified function or line\.\[\r\n\]+With no argument, lists ten more lines after or around previous listing\.\[\r\n\]+\"list -\" lists the ten lines before a previous ten-line listing\.\[\r\n\]+One argument specifies a line, and ten lines are listed around that line\.\[\r\n\]+Two arguments with comma between specify starting and ending lines to list\.\[\r\n\]+Lines can be specified in these ways:\[\r\n\]+  LINENUM, to list around that line in current file,\[\r\n\]+  FILE:LINENUM, to list around that line in that file,\[\r\n\]+  FUNCTION, to list around beginning of that function,\[\r\n\]+  FILE:FUNCTION, to distinguish among like-named static functions\.\[\r\n\]+  \[*\]ADDRESS, to list around the line containing that address\.\[\r\n\]+With two args if one is empty it stands for ten lines away from the other arg\." "help list \"l\" abbreviation"
 # test help list
diff --git a/gdb/testsuite/gdb.base/multi-forks.exp b/gdb/testsuite/gdb.base/multi-forks.exp
index f853180..c09c559 100644
--- a/gdb/testsuite/gdb.base/multi-forks.exp
+++ b/gdb/testsuite/gdb.base/multi-forks.exp
@@ -140,6 +140,19 @@ gdb_test "print pids\[0\]==0 || pids\[1\]==0 || pids\[2\]==0 || pids\[3\]==0" \
 # Now test with detach-on-fork off.
 #
 
+# detach-on-fork isn't implemented on hpux.
+#
+if {![istarget "*-*-linux*"]} then {
+    continue
+}
+
+# Start with a fresh gdb
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
 runto_main
 gdb_breakpoint $exit_bp_loc
 
@@ -152,60 +165,59 @@ gdb_test "set detach off" "" "set detach off"
 
 #
 # We will now run every fork up to the exit bp, 
-# eventually winding up with 16 forks.
+# eventually winding up with 16 inferiors.
 #
 
 for {set i 1} {$i <= 15} {incr i} {
   gdb_test "continue" "Breakpoint .* main .*exit.*" "Run to exit $i"
-  gdb_test "info fork" " 4 .* 3 .* 2 .* 1 .*" "info fork $i"
-  gdb_test "restart $i" "(_dl_sysinfo_int80|fork|__kernel_(v|)syscall).*" \
-      "restart $i"
+  gdb_test "info inferior" " 5 .* 4 .* 3 .* 2 .*" "info inferior $i"
+  gdb_test "inferior $i + 1" "(_dl_sysinfo_int80|fork|__kernel_(v|)syscall).*" \
+      "inferior $i"
 }
 
 gdb_test "continue" "Breakpoint .* main .*exit.*" "Run to exit 16"
-gdb_test "info fork" " 4 .* 3 .* 2 .* 1 .*" "info fork 16"
-gdb_test "restart 0" " main .*" "restart final"
+gdb_test "info inferiors" " 5 .* 4 .* 3 .* 2 .*" "info inferior 16"
+gdb_test "inferior 2" " main .*" "restart final"
 
 #
 # Now we should examine all the pids.
 #
 
 # 
-# Test detach fork
+# Test detach inferior
 # 
 
-# [assumes we're at #0]
-gdb_test "detach fork 1" "Detached .*" "Detach 1"
-gdb_test "detach fork 2" "Detached .*" "Detach 2"
-gdb_test "detach fork 3" "Detached .*" "Detach 3"
-gdb_test "detach fork 4" "Detached .*" "Detach 4"
+# [assumes we're at #1]
+gdb_test "detach inferior 2" "Detaching .*" "Detach 2"
+gdb_test "detach inferior 3" "Detaching .*" "Detach 3"
+gdb_test "detach inferior 4" "Detaching .*" "Detach 4"
+gdb_test "detach inferior 5" "Detaching .*" "Detach 5"
 
 # 
-# Test delete fork
-# 
+# Test kill inferior
+#
 
-gdb_test "delete fork 5" "" "Delete 5"
-gdb_test "info fork 5"   "No fork number 5." "Did delete 5"
-gdb_test "delete fork 6" "" "Delete 6"
-gdb_test "info fork 6"   "No fork number 6." "Did delete 6"
-gdb_test "delete fork 7" "" "Delete 7"
-gdb_test "info fork 7"   "No fork number 7." "Did delete 7"
-gdb_test "delete fork 8" "" "Delete 8"
-gdb_test "info fork 8"   "No fork number 8." "Did delete 8"
-gdb_test "delete fork 9" "" "Delete 9"
-gdb_test "info fork 9"   "No fork number 9." "Did delete 9"
-gdb_test "delete fork 10" "" "Delete 10"
-gdb_test "info fork 10"   "No fork number 10." "Did delete 10"
-gdb_test "delete fork 11" "" "Delete 11"
-gdb_test "info fork 11"   "No fork number 11." "Did delete 11"
-gdb_test "delete fork 12" "" "Delete 12"
-gdb_test "info fork 12"   "No fork number 12." "Did delete 12"
-gdb_test "delete fork 13" "" "Delete 13"
-gdb_test "info fork 13"   "No fork number 13." "Did delete 13"
-gdb_test "delete fork 14" "" "Delete 14"
-gdb_test "info fork 14"   "No fork number 14." "Did delete 14"
-gdb_test "delete fork 15" "" "Delete 15"
-gdb_test "info fork 15"   "No fork number 15." "Did delete 15"
+gdb_test "kill inferior 6" "" "Kill 6"
+gdb_test "info inferior 6" "Inferior ID 6 not known." "Did kill 6"
+gdb_test "kill inferior 7" "" "Kill 7"
+gdb_test "info inferior 7" "Inferior ID 7 not known." "Did kill 7"
+gdb_test "kill inferior 8" "" "Kill 8"
+gdb_test "info inferior 8" "Inferior ID 8 not known." "Did kill 8"
+gdb_test "kill inferior 9" "" "Kill 9"
+gdb_test "info inferior 9" "Inferior ID 9 not known." "Did kill 9"
+gdb_test "kill inferior 10" "" "Kill 10"
+gdb_test "info inferior 10" "Inferior ID 10 not known." "Did kill 10"
+gdb_test "kill inferior 11" "" "Kill 11"
+gdb_test "info inferior 11" "Inferior ID 11 not known." "Did kill 11"
+gdb_test "kill inferior 12" "" "Kill 12"
+gdb_test "info inferior 12" "Inferior ID 12 not known." "Did kill 12"
+gdb_test "kill inferior 13" "" "Kill 13"
+gdb_test "info inferior 13" "Inferior ID 13 not known." "Did kill 13"
+gdb_test "kill inferior 14" "" "Kill 14"
+gdb_test "info inferior 14" "Inferior ID 14 not known." "Did kill 14"
+gdb_test "kill inferior 15" "" "Kill 15"
+gdb_test "info inferior 15" "Inferior ID 15 not known." "Did kill 15"
+gdb_test "kill inferior 16" "" "Kill 16"
+gdb_test "info inferior 16" "Inferior ID 16 not known." "Did kill 16"
 
 return 0
-
diff --git a/gdb/thread.c b/gdb/thread.c
index 5361771..a7ac3c8 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -428,6 +428,18 @@ first_thread_of_process (int pid)
   return ret;
 }
 
+struct thread_info *
+any_thread_of_process (int pid)
+{
+  struct thread_info *tp;
+
+  for (tp = thread_list; tp; tp = tp->next)
+    if (ptid_get_pid (tp->ptid) == pid)
+      return tp;
+
+  return NULL;
+}
+
 /* Print a list of thread ids currently known, and the total number of
    threads. To be used from within catch_errors. */
 static int