gdb/ravenscar-thread.c - native_client/nacl-gdb - Git at Google

 /* Ada Ravenscar thread support.

    Copyright 2004, 2009-2012 Free Software Foundation, Inc.

    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 3 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, see <http://www.gnu.org/licenses/>.  */

 #include "defs.h"
 #include "gdbcore.h"
 #include "gdbthread.h"
 #include "ada-lang.h"
 #include "target.h"
 #include "inferior.h"
 #include "command.h"
 #include "ravenscar-thread.h"
 #include "observer.h"
 #include "gdb_string.h"
 #include "gdbcmd.h"
 #include "top.h"
 #include "regcache.h"

 /* If non-null, ravenscar task support is enabled.  */
 static int ravenscar_task_support = 1;

 /* Non-null if the ravenscar thread layer has been pushed on the target
    stack.  */
 static int ravenscar_is_open = 0;

 /* This module's target-specific operations.  */
 static struct target_ops ravenscar_ops;

 /* Some base target uses a special value for the null PID (exempli gratia
    remote).  */
 static ptid_t base_magic_null_ptid;

 /* Ptid of the inferior as seen by the process stratum.  */
 static ptid_t base_ptid;

 static const char running_thread_name[] = "__gnat_running_thread_table";

 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
 static const char first_task_name[] = "system__tasking__debug__first_task";

 static const char ravenscar_runtime_initializer[] =
   "system__bb__threads__initialize";

 static struct observer *update_target_observer = NULL;

 /* Architecture-specific hooks.  */
 static struct ravenscar_arch_ops* current_arch_ops;

 static void ravenscar_find_new_threads (struct target_ops *ops);
 static ptid_t ravenscar_running_thread (void);
 static char *ravenscar_extra_thread_info (struct thread_info *tp);
 static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
 static void ravenscar_fetch_registers (struct target_ops *ops,
                                        struct regcache *regcache, int regnum);
 static void ravenscar_store_registers (struct target_ops *ops,
                                        struct regcache *regcache, int regnum);
 static void ravenscar_prepare_to_store (struct regcache *regcache);
 static void ravenscar_initialize  (char *name, int from_tty);
 static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
 			      enum target_signal siggnal);
 static void ravenscar_mourn_inferior (struct target_ops *ops);
 static void ravenscar_update_inferior_ptid (void);
 static int has_ravenscar_runtime (void);
 static int ravenscar_runtime_initialized (void);
 static void ravenscar_inferior_created (struct target_ops *target,
 					int from_tty);

 /* Fetch the ravenscar running thread from target memory and
    update inferior_ptid accordingly.  */

 static void
 ravenscar_update_inferior_ptid (void)
 {
   base_ptid = inferior_ptid;

   /* If the runtime has not been initialized yet, the inferior_ptid is
      the only ptid that there is.  */
   if (!ravenscar_runtime_initialized ())
     return;

   /* Make sure we set base_ptid before calling ravenscar_running_thread
      as the latter relies on it.  */
   inferior_ptid = ravenscar_running_thread ();
   gdb_assert (!ptid_equal (inferior_ptid, null_ptid));

   /* The running thread may not have been added to
      system.tasking.debug's list yet; so ravenscar_find_new_threads
      may not always add it to the thread list.  Add it here.  */
   if (!find_thread_ptid (inferior_ptid))
     add_thread (inferior_ptid);
 }

 /* The Ravenscar Runtime exports a symbol which contains the ID of
    the thread that is currently running.  Try to locate that symbol
    and return its associated minimal symbol.
    Return NULL if not found.  */

 static struct minimal_symbol *
 get_running_thread_msymbol (void)
 {
   struct minimal_symbol *msym;

   msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
   if (!msym)
     /* Older versions of the GNAT runtime were using a different
        (less ideal) name for the symbol where the active thread ID
        is stored.  If we couldn't find the symbol using the latest
        name, then try the old one.  */
     msym = lookup_minimal_symbol ("running_thread", NULL, NULL);

   return msym;
 }

 /* Return True if the Ada Ravenscar run-time can be found in the
    application.  */

 static int
 has_ravenscar_runtime (void)
 {
   struct minimal_symbol *msym_ravenscar_runtime_initializer =
     lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
   struct minimal_symbol *msym_known_tasks =
     lookup_minimal_symbol (known_tasks_name, NULL, NULL);
   struct minimal_symbol *msym_first_task =
     lookup_minimal_symbol (first_task_name, NULL, NULL);
   struct minimal_symbol *msym_running_thread = get_running_thread_msymbol ();

   return (msym_ravenscar_runtime_initializer
 	  && (msym_known_tasks || msym_first_task)
 	  && msym_running_thread);
 }

 /* Return True if the Ada Ravenscar run-time can be found in the
    application, and if it has been initialized on target.  */

 static int
 ravenscar_runtime_initialized (void)
 {
   return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
 }

 /* Return the ID of the thread that is currently running.
    Return 0 if the ID could not be determined.  */

 static CORE_ADDR
 get_running_thread_id (void)
 {
   const struct minimal_symbol *object_msym = get_running_thread_msymbol ();
   int object_size;
   int buf_size;
   char *buf;
   CORE_ADDR object_addr;
   struct type *builtin_type_void_data_ptr =
     builtin_type (target_gdbarch)->builtin_data_ptr;

   if (!object_msym)
     return 0;

   object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
   object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
   buf_size = object_size;
   buf = alloca (buf_size);
   read_memory (object_addr, buf, buf_size);
   return extract_typed_address (buf, builtin_type_void_data_ptr);
 }

 static void
 ravenscar_close (int quitting)
 {
   ravenscar_is_open = 0;
 }

 static void
 ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
 		  enum target_signal siggnal)
 {
   struct target_ops *beneath = find_target_beneath (ops);

   inferior_ptid = base_ptid;
   beneath->to_resume (beneath, base_ptid, step, siggnal);
 }

 static ptid_t
 ravenscar_wait (struct target_ops *ops, ptid_t ptid,
                 struct target_waitstatus *status,
                 int options)
 {
   struct target_ops *beneath = find_target_beneath (ops);

   inferior_ptid = base_ptid;
   beneath->to_wait (beneath, base_ptid, status, 0);
   ravenscar_find_new_threads (ops);
   ravenscar_update_inferior_ptid ();
   return inferior_ptid;
 }

 /* Add the thread associated to the given TASK to the thread list
    (if the thread has already been added, this is a no-op).  */

 static void
 ravenscar_add_thread (struct ada_task_info *task)
 {
   if (find_thread_ptid (task->ptid) == NULL)
     add_thread (task->ptid);
 }

 static void
 ravenscar_find_new_threads (struct target_ops *ops)
 {
   ada_build_task_list ();

   /* Do not clear the thread list before adding the Ada task, to keep
      the thread that the process stratum has included into it
      (base_ptid) and the running thread, that may not have been included
      to system.tasking.debug's list yet.  */

   iterate_over_live_ada_tasks (ravenscar_add_thread);
 }

 static ptid_t
 ravenscar_running_thread (void)
 {
   CORE_ADDR tid = get_running_thread_id ();

   if (tid == 0)
     return null_ptid;
   else
     return ptid_build (ptid_get_pid (base_ptid), 0, tid);
 }

 static char *
 ravenscar_extra_thread_info (struct thread_info *tp)
 {
   return "Ravenscar task";
 }

 static int
 ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
 {
   /* Ravenscar tasks are non-terminating.  */
   return 1;
 }

 static char *
 ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
 {
   static char buf[30];

   snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
   return buf;
 }

 static void
 ravenscar_fetch_registers (struct target_ops *ops,
                            struct regcache *regcache, int regnum)
 {
   struct target_ops *beneath = find_target_beneath (ops);

   if (!ravenscar_runtime_initialized ()
       || ptid_equal (inferior_ptid, base_magic_null_ptid)
       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
     beneath->to_fetch_registers (beneath, regcache, regnum);
   else
     current_arch_ops->to_fetch_registers (regcache, regnum);
 }

 static void
 ravenscar_store_registers (struct target_ops *ops,
                            struct regcache *regcache, int regnum)
 {
   struct target_ops *beneath = find_target_beneath (ops);

   if (!ravenscar_runtime_initialized ()
       || ptid_equal (inferior_ptid, base_magic_null_ptid)
       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
     beneath->to_store_registers (beneath, regcache, regnum);
   else
     current_arch_ops->to_store_registers (regcache, regnum);
 }

 static void
 ravenscar_prepare_to_store (struct regcache *regcache)
 {
   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);

   if (!ravenscar_runtime_initialized ()
       || ptid_equal (inferior_ptid, base_magic_null_ptid)
       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
     beneath->to_prepare_to_store (regcache);
   else
     current_arch_ops->to_prepare_to_store (regcache);
 }

 static void
 ravenscar_mourn_inferior (struct target_ops *ops)
 {
   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);

   base_ptid = null_ptid;
   beneath->to_mourn_inferior (beneath);
   unpush_target (&ravenscar_ops);
 }

 /* Observer on inferior_created: push ravenscar thread stratum if needed.  */

 static void
 ravenscar_inferior_created (struct target_ops *target, int from_tty)
 {
   if (ravenscar_task_support
       && has_ravenscar_runtime ())
     ravenscar_initialize (NULL, 0);
 }

 void
 ravenscar_register_arch_ops (struct ravenscar_arch_ops *ops)
 {
   /* FIXME: To be clean, we would need to handle a list of
      architectures, just like in remote-wtx-hw.c.  However, for now the
      only Ravenscar run-time for bare board that is implemented in
      GNAT is for only one architecture: erc32-elf.  So no need to care about
      that for now...  */
   current_arch_ops = ops;
 }

 /* Initialize Ravenscar support.  */

 static void
 ravenscar_initialize (char *name, int from_tty)
 {
   if (ravenscar_is_open)
     return;

   base_magic_null_ptid = inferior_ptid;
   ravenscar_update_inferior_ptid ();
   push_target (&ravenscar_ops);
   ravenscar_is_open = 1;
 }

 static ptid_t
 ravenscar_get_ada_task_ptid (long lwp, long thread)
 {
   return ptid_build (ptid_get_pid (base_ptid), 0, thread);
 }

 static void
 init_ravenscar_thread_ops (void)
 {
   ravenscar_ops.to_shortname = "ravenscar";
   ravenscar_ops.to_longname = "Ravenscar tasks.";
   ravenscar_ops.to_doc = "Ravenscar tasks support.";
   ravenscar_ops.to_close = ravenscar_close;
   ravenscar_ops.to_resume = ravenscar_resume;
   ravenscar_ops.to_wait = ravenscar_wait;
   ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
   ravenscar_ops.to_store_registers = ravenscar_store_registers;
   ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
   ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
   ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
   ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
   ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
   ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
   ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
   ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
   ravenscar_ops.to_has_memory = default_child_has_memory;
   ravenscar_ops.to_has_stack = default_child_has_stack;
   ravenscar_ops.to_has_registers = default_child_has_registers;
   ravenscar_ops.to_has_execution = default_child_has_execution;
   ravenscar_ops.to_stratum = thread_stratum;
   ravenscar_ops.to_magic = OPS_MAGIC;
 }

 /* Command-list for the "set/show ravenscar" prefix command.  */
 static struct cmd_list_element *set_ravenscar_list;
 static struct cmd_list_element *show_ravenscar_list;

 /* Implement the "set ravenscar" prefix command.  */

 static void
 set_ravenscar_command (char *arg, int from_tty)
 {
   printf_unfiltered (_(\
 "\"set ravenscar\" must be followed by the name of a setting.\n"));
   help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
 }

 /* Implement the "show ravenscar" prefix command.  */

 static void
 show_ravenscar_command (char *args, int from_tty)
 {
   cmd_show_list (show_ravenscar_list, from_tty, "");
 }

 /* Implement the "show ravenscar task-switching" command.  */

 static void
 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
 				       struct cmd_list_element *c,
 				       const char *value)
 {
   if (ravenscar_task_support)
     fprintf_filtered (file, _("\
 Support for Ravenscar task/thread switching is enabled\n"));
   else
     fprintf_filtered (file, _("\
 Support for Ravenscar task/thread switching is disabled\n"));
 }

 /* Module startup initialization function, automagically called by
    init.c.  */

 void
 _initialize_ravenscar (void)
 {
   init_ravenscar_thread_ops ();
   base_ptid = null_ptid;

   /* Notice when the inferior is created in order to push the
      ravenscar ops if needed.  */
   observer_attach_inferior_created (ravenscar_inferior_created);

   add_target (&ravenscar_ops);

   add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
                   _("Prefix command for changing Ravenscar-specific settings"),
                   &set_ravenscar_list, "set ravenscar ", 0, &setlist);

   add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
                   _("Prefix command for showing Ravenscar-specific settings"),
                   &show_ravenscar_list, "show ravenscar ", 0, &showlist);

   add_setshow_boolean_cmd ("task-switching", class_obscure,
                            &ravenscar_task_support, _("\
 Enable or disable support for GNAT Ravenscar tasks"), _("\
 Show whether support for GNAT Ravenscar tasks is enabled"),
                            _("\
 Enable or disable support for task/thread switching with the GNAT\n\
 Ravenscar run-time library for bareboard configuration."),
 			   NULL, show_ravenscar_task_switching_command,
 			   &set_ravenscar_list, &show_ravenscar_list);
 }
	/* Ada Ravenscar thread support.

	Copyright 2004, 2009-2012 Free Software Foundation, Inc.

	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 3 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, see <http://www.gnu.org/licenses/>. */

	#include "defs.h"
	#include "gdbcore.h"
	#include "gdbthread.h"
	#include "ada-lang.h"
	#include "target.h"
	#include "inferior.h"
	#include "command.h"
	#include "ravenscar-thread.h"
	#include "observer.h"
	#include "gdb_string.h"
	#include "gdbcmd.h"
	#include "top.h"
	#include "regcache.h"

	/* If non-null, ravenscar task support is enabled. */
	static int ravenscar_task_support = 1;

	/* Non-null if the ravenscar thread layer has been pushed on the target
	stack. */
	static int ravenscar_is_open = 0;

	/* This module's target-specific operations. */
	static struct target_ops ravenscar_ops;

	/* Some base target uses a special value for the null PID (exempli gratia
	remote). */
	static ptid_t base_magic_null_ptid;

	/* Ptid of the inferior as seen by the process stratum. */
	static ptid_t base_ptid;

	static const char running_thread_name[] = "__gnat_running_thread_table";

	static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
	static const char first_task_name[] = "system__tasking__debug__first_task";

	static const char ravenscar_runtime_initializer[] =
	"system__bb__threads__initialize";

	static struct observer *update_target_observer = NULL;

	/* Architecture-specific hooks. */
	static struct ravenscar_arch_ops* current_arch_ops;

	static void ravenscar_find_new_threads (struct target_ops *ops);
	static ptid_t ravenscar_running_thread (void);
	static char ravenscar_extra_thread_info (struct thread_info tp);
	static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
	static void ravenscar_fetch_registers (struct target_ops *ops,
	struct regcache *regcache, int regnum);
	static void ravenscar_store_registers (struct target_ops *ops,
	struct regcache *regcache, int regnum);
	static void ravenscar_prepare_to_store (struct regcache *regcache);
	static void ravenscar_initialize (char *name, int from_tty);
	static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
	enum target_signal siggnal);
	static void ravenscar_mourn_inferior (struct target_ops *ops);
	static void ravenscar_update_inferior_ptid (void);
	static int has_ravenscar_runtime (void);
	static int ravenscar_runtime_initialized (void);
	static void ravenscar_inferior_created (struct target_ops *target,
	int from_tty);

	/* Fetch the ravenscar running thread from target memory and
	update inferior_ptid accordingly. */

	static void
	ravenscar_update_inferior_ptid (void)
	{
	base_ptid = inferior_ptid;

	/* If the runtime has not been initialized yet, the inferior_ptid is
	the only ptid that there is. */
	if (!ravenscar_runtime_initialized ())
	return;

	/* Make sure we set base_ptid before calling ravenscar_running_thread
	as the latter relies on it. */
	inferior_ptid = ravenscar_running_thread ();
	gdb_assert (!ptid_equal (inferior_ptid, null_ptid));

	/* The running thread may not have been added to
	system.tasking.debug's list yet; so ravenscar_find_new_threads
	may not always add it to the thread list. Add it here. */
	if (!find_thread_ptid (inferior_ptid))
	add_thread (inferior_ptid);
	}

	/* The Ravenscar Runtime exports a symbol which contains the ID of
	the thread that is currently running. Try to locate that symbol
	and return its associated minimal symbol.
	Return NULL if not found. */

	static struct minimal_symbol *
	get_running_thread_msymbol (void)
	{
	struct minimal_symbol *msym;

	msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
	if (!msym)
	/* Older versions of the GNAT runtime were using a different
	(less ideal) name for the symbol where the active thread ID
	is stored. If we couldn't find the symbol using the latest
	name, then try the old one. */
	msym = lookup_minimal_symbol ("running_thread", NULL, NULL);

	return msym;
	}

	/* Return True if the Ada Ravenscar run-time can be found in the
	application. */

	static int
	has_ravenscar_runtime (void)
	{
	struct minimal_symbol *msym_ravenscar_runtime_initializer =
	lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
	struct minimal_symbol *msym_known_tasks =
	lookup_minimal_symbol (known_tasks_name, NULL, NULL);
	struct minimal_symbol *msym_first_task =
	lookup_minimal_symbol (first_task_name, NULL, NULL);
	struct minimal_symbol *msym_running_thread = get_running_thread_msymbol ();

	return (msym_ravenscar_runtime_initializer
	&& (msym_known_tasks \|\| msym_first_task)
	&& msym_running_thread);
	}

	/* Return True if the Ada Ravenscar run-time can be found in the
	application, and if it has been initialized on target. */

	static int
	ravenscar_runtime_initialized (void)
	{
	return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
	}

	/* Return the ID of the thread that is currently running.
	Return 0 if the ID could not be determined. */

	static CORE_ADDR
	get_running_thread_id (void)
	{
	const struct minimal_symbol *object_msym = get_running_thread_msymbol ();
	int object_size;
	int buf_size;
	char *buf;
	CORE_ADDR object_addr;
	struct type *builtin_type_void_data_ptr =
	builtin_type (target_gdbarch)->builtin_data_ptr;

	if (!object_msym)
	return 0;

	object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
	object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
	buf_size = object_size;
	buf = alloca (buf_size);
	read_memory (object_addr, buf, buf_size);
	return extract_typed_address (buf, builtin_type_void_data_ptr);
	}

	static void
	ravenscar_close (int quitting)
	{
	ravenscar_is_open = 0;
	}

	static void
	ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
	enum target_signal siggnal)
	{
	struct target_ops *beneath = find_target_beneath (ops);

	inferior_ptid = base_ptid;
	beneath->to_resume (beneath, base_ptid, step, siggnal);
	}

	static ptid_t
	ravenscar_wait (struct target_ops *ops, ptid_t ptid,
	struct target_waitstatus *status,
	int options)
	{
	struct target_ops *beneath = find_target_beneath (ops);

	inferior_ptid = base_ptid;
	beneath->to_wait (beneath, base_ptid, status, 0);
	ravenscar_find_new_threads (ops);
	ravenscar_update_inferior_ptid ();
	return inferior_ptid;
	}

	/* Add the thread associated to the given TASK to the thread list
	(if the thread has already been added, this is a no-op). */

	static void
	ravenscar_add_thread (struct ada_task_info *task)
	{
	if (find_thread_ptid (task->ptid) == NULL)
	add_thread (task->ptid);
	}

	static void
	ravenscar_find_new_threads (struct target_ops *ops)
	{
	ada_build_task_list ();

	/* Do not clear the thread list before adding the Ada task, to keep
	the thread that the process stratum has included into it
	(base_ptid) and the running thread, that may not have been included
	to system.tasking.debug's list yet. */

	iterate_over_live_ada_tasks (ravenscar_add_thread);
	}

	static ptid_t
	ravenscar_running_thread (void)
	{
	CORE_ADDR tid = get_running_thread_id ();

	if (tid == 0)
	return null_ptid;
	else
	return ptid_build (ptid_get_pid (base_ptid), 0, tid);
	}

	static char *
	ravenscar_extra_thread_info (struct thread_info *tp)
	{
	return "Ravenscar task";
	}

	static int
	ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
	{
	/* Ravenscar tasks are non-terminating. */
	return 1;
	}

	static char *
	ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
	{
	static char buf[30];

	snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
	return buf;
	}

	static void
	ravenscar_fetch_registers (struct target_ops *ops,
	struct regcache *regcache, int regnum)
	{
	struct target_ops *beneath = find_target_beneath (ops);

	if (!ravenscar_runtime_initialized ()
	\|\| ptid_equal (inferior_ptid, base_magic_null_ptid)
	\|\| ptid_equal (inferior_ptid, ravenscar_running_thread ()))
	beneath->to_fetch_registers (beneath, regcache, regnum);
	else
	current_arch_ops->to_fetch_registers (regcache, regnum);
	}

	static void
	ravenscar_store_registers (struct target_ops *ops,
	struct regcache *regcache, int regnum)
	{
	struct target_ops *beneath = find_target_beneath (ops);

	if (!ravenscar_runtime_initialized ()
	\|\| ptid_equal (inferior_ptid, base_magic_null_ptid)
	\|\| ptid_equal (inferior_ptid, ravenscar_running_thread ()))
	beneath->to_store_registers (beneath, regcache, regnum);
	else
	current_arch_ops->to_store_registers (regcache, regnum);
	}

	static void
	ravenscar_prepare_to_store (struct regcache *regcache)
	{
	struct target_ops *beneath = find_target_beneath (&ravenscar_ops);

	if (!ravenscar_runtime_initialized ()
	\|\| ptid_equal (inferior_ptid, base_magic_null_ptid)
	\|\| ptid_equal (inferior_ptid, ravenscar_running_thread ()))
	beneath->to_prepare_to_store (regcache);
	else
	current_arch_ops->to_prepare_to_store (regcache);
	}

	static void
	ravenscar_mourn_inferior (struct target_ops *ops)
	{
	struct target_ops *beneath = find_target_beneath (&ravenscar_ops);

	base_ptid = null_ptid;
	beneath->to_mourn_inferior (beneath);
	unpush_target (&ravenscar_ops);
	}

	/* Observer on inferior_created: push ravenscar thread stratum if needed. */

	static void
	ravenscar_inferior_created (struct target_ops *target, int from_tty)
	{
	if (ravenscar_task_support
	&& has_ravenscar_runtime ())
	ravenscar_initialize (NULL, 0);
	}

	void
	ravenscar_register_arch_ops (struct ravenscar_arch_ops *ops)
	{
	/* FIXME: To be clean, we would need to handle a list of
	architectures, just like in remote-wtx-hw.c. However, for now the
	only Ravenscar run-time for bare board that is implemented in
	GNAT is for only one architecture: erc32-elf. So no need to care about
	that for now... */
	current_arch_ops = ops;
	}

	/* Initialize Ravenscar support. */

	static void
	ravenscar_initialize (char *name, int from_tty)
	{
	if (ravenscar_is_open)
	return;

	base_magic_null_ptid = inferior_ptid;
	ravenscar_update_inferior_ptid ();
	push_target (&ravenscar_ops);
	ravenscar_is_open = 1;
	}

	static ptid_t
	ravenscar_get_ada_task_ptid (long lwp, long thread)
	{
	return ptid_build (ptid_get_pid (base_ptid), 0, thread);
	}

	static void
	init_ravenscar_thread_ops (void)
	{
	ravenscar_ops.to_shortname = "ravenscar";
	ravenscar_ops.to_longname = "Ravenscar tasks.";
	ravenscar_ops.to_doc = "Ravenscar tasks support.";
	ravenscar_ops.to_close = ravenscar_close;
	ravenscar_ops.to_resume = ravenscar_resume;
	ravenscar_ops.to_wait = ravenscar_wait;
	ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
	ravenscar_ops.to_store_registers = ravenscar_store_registers;
	ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
	ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
	ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
	ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
	ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
	ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
	ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
	ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
	ravenscar_ops.to_has_memory = default_child_has_memory;
	ravenscar_ops.to_has_stack = default_child_has_stack;
	ravenscar_ops.to_has_registers = default_child_has_registers;
	ravenscar_ops.to_has_execution = default_child_has_execution;
	ravenscar_ops.to_stratum = thread_stratum;
	ravenscar_ops.to_magic = OPS_MAGIC;
	}

	/* Command-list for the "set/show ravenscar" prefix command. */
	static struct cmd_list_element *set_ravenscar_list;
	static struct cmd_list_element *show_ravenscar_list;

	/* Implement the "set ravenscar" prefix command. */

	static void
	set_ravenscar_command (char *arg, int from_tty)
	{
	printf_unfiltered (_(\
	"\"set ravenscar\" must be followed by the name of a setting.\n"));
	help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
	}

	/* Implement the "show ravenscar" prefix command. */

	static void
	show_ravenscar_command (char *args, int from_tty)
	{
	cmd_show_list (show_ravenscar_list, from_tty, "");
	}

	/* Implement the "show ravenscar task-switching" command. */

	static void
	show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
	struct cmd_list_element *c,
	const char *value)
	{
	if (ravenscar_task_support)
	fprintf_filtered (file, _("\
	Support for Ravenscar task/thread switching is enabled\n"));
	else
	fprintf_filtered (file, _("\
	Support for Ravenscar task/thread switching is disabled\n"));
	}

	/* Module startup initialization function, automagically called by
	init.c. */

	void
	_initialize_ravenscar (void)
	{
	init_ravenscar_thread_ops ();
	base_ptid = null_ptid;

	/* Notice when the inferior is created in order to push the
	ravenscar ops if needed. */
	observer_attach_inferior_created (ravenscar_inferior_created);

	add_target (&ravenscar_ops);

	add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
	_("Prefix command for changing Ravenscar-specific settings"),
	&set_ravenscar_list, "set ravenscar ", 0, &setlist);

	add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
	_("Prefix command for showing Ravenscar-specific settings"),
	&show_ravenscar_list, "show ravenscar ", 0, &showlist);

	add_setshow_boolean_cmd ("task-switching", class_obscure,
	&ravenscar_task_support, _("\
	Enable or disable support for GNAT Ravenscar tasks"), _("\
	Show whether support for GNAT Ravenscar tasks is enabled"),
	_("\
	Enable or disable support for task/thread switching with the GNAT\n\
	Ravenscar run-time library for bareboard configuration."),
	NULL, show_ravenscar_task_switching_command,
	&set_ravenscar_list, &show_ravenscar_list);
	}