* Makefile.in (SFILES): Add new and missed files.

(target_descriptions_h): New.
	(COMMON_OBS): Add target-descriptions.o.
	(arch-utils.o, infcmd.o, remote.o, target.o): Update.
	(target-descriptions.o): New.
	* arch-utils.c (gdbarch_info_fill): Check for a target
	description.
	* target-descriptions.c, target-descriptions.h: New files.
	* gdbarch.sh: Add target_desc to info.  Declare it in gdbarch.h.
	Correct typos.
	(gdbarch_list_lookup_by_info): Check target_desc.
	* gdbarch.c, gdbarch.h: Regenerated.
	* target.c (update_current_target): Mention to_read_description.
	(target_pre_inferior): Call target_clear_description.
	(target_read_description): New.
	* target.h (struct target_ops): Add to_read_description.
	(target_read_description): New prototype.
	* infcmd.c (post_create_inferior): Call target_find_description.
	* remote.c (remote_open_1): Likewise.
	(extended_remote_create_inferior): Add a comment.
	(extended_remote_async_create_inferior): Likewise.

gdb/target.c

@@ -40,6 +40,7 @@
 #include "gdb_assert.h"
 #include "gdbcore.h"
 #include "exceptions.h"
+#include "target-descriptions.h"
 
 static void target_info (char *, int);
 
@@ -464,6 +465,7 @@ update_current_target (void)
       INHERIT (to_find_memory_regions, t);
       INHERIT (to_make_corefile_notes, t);
       INHERIT (to_get_thread_local_address, t);
+      /* Do not inherit to_read_description.  */
       INHERIT (to_magic, t);
       /* Do not inherit to_memory_map.  */
       /* Do not inherit to_flash_erase.  */
@@ -641,6 +643,7 @@ update_current_target (void)
   de_fault (to_async,
 	    (void (*) (void (*) (enum inferior_event_type, void*), void*))
 	    tcomplain);
+  current_target.to_read_description = NULL;
 #undef de_fault
 
   /* Finally, position the target-stack beneath the squashed
@@ -1602,6 +1605,8 @@ void
 target_pre_inferior (int from_tty)
 {
   invalidate_target_mem_regions ();
+
+  target_clear_description ();
 }
 
 /* This is to be called by the open routine before it does
@@ -1689,6 +1694,27 @@ target_follow_fork (int follow_child)
 		  "could not find a target to follow fork");
 }
 
+/* Look for a target which can describe architectural features, starting
+   from TARGET.  If we find one, return its description.  */
+
+const struct target_desc *
+target_read_description (struct target_ops *target)
+{
+  struct target_ops *t;
+
+  for (t = target; t != NULL; t = t->beneath)
+    if (t->to_read_description != NULL)
+      {
+	const struct target_desc *tdesc;
+
+	tdesc = t->to_read_description (t);
+	if (tdesc)
+	  return tdesc;
+      }
+
+  return NULL;
+}
+
 /* Look through the list of possible targets for a target that can
    execute a run or attach command without any other data.  This is
    used to locate the default process stratum.