Re: gdb and libc debug symbols

[Timo Buhrmester <fstd.lkml%gmail.com@localhost>]

> > I wonder if you need to set DBG somehow also, to specify the flags that
> > go in the debug lib.  But it seems it should default to the right thing.
> Will try DBG=-g and report back, thanks.
I removed MKDEBUG and MKDEBUGLIB, added DBG= -g -O2, rebuilt and installed 
everything (`distribution').
(BTW, without the -O2, I got linker errors (some objc_* symbols missing).

Now, gdb does appear to load debug symbols:
| [...]
| Reading symbols from /usr/lib/libc.so.12...done.
| Loaded symbols for /usr/lib/libc.so.12
| [...]

But still no additinal information the backtrace.
| (gdb) bt full
| #0  0x00007f7ff7439538 in read () from /usr/lib/libc.so.12
| No symbol table info available.
| [...]

Is this it, or should there be more?  If not, how would I go about determining 
what source line address `0x00007f7ff7439538' refers to?

I'm totally lost.