debugging in-build-tree glibc

["David S. Miller" <davem at davemloft dot net>]

I know information on how people do this effectively must
exist somewhere, but I'm having a hard time finding it.

Currently I just run /path/to/build-$(PLATFORM)/elf/ld-linux.so.2
directly under GDB and replicate the --library-path, executable
path, et al. arguments that the build itself uses.

This allows me to debug but since we're debugging ld.so directly
the loading of new files does not get caught by gdb so no symbol
information is available for anything outside of ld.so itself.
If I really need the symbol information I look at the output of
/proc/${PID-of-ld-linux.so.2}/maps and lookup the symbol names
manually.  To say the least, this is cumbersome...

It would be nice, whatever the answer is, for this to be
documented in some top-level libc/FOO.txt file. I know I wouldn't
be the only person to find this useful.