Re: [PATCH] fix vsyscall unwind information

[David Mosberger-Tang]

>>>>> On Mon, 5 May 2003 09:34:44 -0700, Richard Henderson <[e-mail]> said:

  Richard> On Mon, May 05, 2003 at 08:05:58AM -0700, David
  Richard> Mosberger-Tang wrote: Why?  Certainly it isn't needed for
  Richard> x86.
  >>  Certain applications (such as debuggers) want to know.  Sure,
  >> you can do symbol matching (if you have the symbol table) or
  >> code-reading (assuming you know the exact sigreturn sequence),
  >> but having a marker would be more reliable and faster.

  Richard> Eh.  The whole point was to *eliminate* the special cases.

Signal handlers have special significance on UNIX-like operating
systems.  An application might want to know when it's in a signal
frame.  If it's a problem to do this with DWARF2 info, fine.  If not,
please consider adding a marker (my current version of libunwind for
x86 does code-reading to detect signal-frames; not pretty, but it
works reasonable well in practice; it would be nicer to get rid of the
code-reading though, in the future).

	--david