gdb/

        * frame.c (get_frame_id): Default to outer_frame_id if the this_id
        method does not supply an ID.  Assert that the result is not
        null_frame_id.
        (outer_frame_id): New.
        (frame_id_p): Accept outer_frame_id.
        (frame_id_eq): Allow outer_frame_id to be equal to itself.
        (frame_find_by_id): Revert previous local workarounds.
        (get_prev_frame_1): Adjust end-of-stack check to test outer_frame_id.
        * frame.h (null_frame_id, frame_id_p): Update comments.
        (outer_frame_id): Declare.
        * infrun.c (handle_inferior_event): Do not treat all steps from the
        outermost frame as subroutine calls.

        * libunwind-frame.c (libunwind_frame_this_id): Do not clear THIS_ID.
        * hppa-tdep.c (hppa_stub_frame_this_id): Likewise.
        * ia64-tdep.c (ia64_frame_this_id): Likewise.
        (ia64_libunwind_frame_this_id, ia64_libunwind_sigtramp_frame_this_id):
        Use outer_frame_id instead of null_frame_id.
        * amd64obsd-tdep.c (amd64obsd_trapframe_cache): Use outer_frame_id.
        * i386obsd-tdep.c (i386obsd_trapframe_cache): Likewise.
        * inline-frame.c (inline_frame_this_id): Refuse outer_frame_id.
        * thread.c (restore_selected_frame): Update comment and remove
        frame_id_p check.

        gdb/doc/
        * gdbint.texinfo (Unwinding the Frame ID): Reference outer_frame_id.

1 files changed, 9 insertions, 1 deletions

diff --git a/gdb/doc/gdbint.texinfo b/gdb/doc/gdbint.texinfo
index e706caa..c2be3f7 100644
--- a/gdb/doc/gdbint.texinfo
+++ b/gdb/doc/gdbint.texinfo
@@ -2042,9 +2042,17 @@ address as its caller.  On some platforms, a third address is part of
 the ID to further disambiguate frames---for instance, on IA-64
 the separate register stack address is included in the ID.
 
-An invalid frame ID (@code{null_frame_id}) returned from the
+An invalid frame ID (@code{outer_frame_id}) returned from the
 @code{this_id} method means to stop unwinding after this frame.
 
+@code{null_frame_id} is another invalid frame ID which should be used
+when there is no frame.  For instance, certain breakpoints are attached
+to a specific frame, and that frame is identified through its frame ID
+(we use this to implement the "finish" command).  Using
+@code{null_frame_id} as the frame ID for a given breakpoint means
+that the breakpoint is not specific to any frame.  The @code{this_id}
+method should never return @code{null_frame_id}.
+
 @section Unwinding Registers
 
 Each unwinder includes a @code{prev_register} method.  This method