Obscure .eh_frame debug info question.

[Tom Horsley]

On Thu, 21 May 2009 10:34:18 -0700
Ulrich Drepper wrote:

> You don't give any kind of details so you cannot get help.  If you find
> a problem with the frame info file a bug.  But be sure it's a problem.

Its obviously not a problem, since gdb can walkback through the frame
in question, I just can't figure out what implicit undocumented information
gdb must be using to initialize the process of interpreting the frame
info. Specifically the bizarre little macros such as lll_lock()
from nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h which
have the hand coded frame descriptions from the LLL_STUB_UNWIND_INFO_5
macro (and similar friends).

Someday I'll find a good place to set a breakpoint in gdb itself so
I can step through the algorithm (since gdb is actually the only
standard "document" that matters), but just finding that place is
a task akin to cleaning the Augean stables :-).