+ see the comments in infrun.c.
+ m;CORE_ADDR;displaced_step_location;thread_info *;thread;;NULL;;(! gdbarch->displaced_step_location) != (! gdbarch->displaced_step_copy_insn)
+ m;CORE_ADDR;displaced_step_release_location;CORE_ADDR;addr;;NULL;;(! gdbarch->displaced_step_location) != (! gdbarch->displaced_step_copy_insn) */
+
+typedef displaced_step_prepare_status (gdbarch_displaced_step_prepare_ftype) (struct gdbarch *gdbarch, thread_info *thread);
+extern displaced_step_prepare_status gdbarch_displaced_step_prepare (struct gdbarch *gdbarch, thread_info *thread);
+extern void set_gdbarch_displaced_step_prepare (struct gdbarch *gdbarch, gdbarch_displaced_step_prepare_ftype *displaced_step_prepare);