Best way to add DBX_USE_BINCL to a.out toolchains?

[jtc at redback dot com (J.T. Conklin)]

While I prefer to use ELF-based toolchains for embedded targets, some-
times legacy constraints dictate otherwise.  In my case, it's the fact
that we're using an old version of vxWorks/i386.  I'm sure that others
have reasons why it's difficult or impossible to transition from a.out
to ELF.  I mention this only to head off any suggestions that switching
to ELF will solve all the worlds problems...

After I implemented profiling for our vxWorks/i386-based systems, I
found gprof was taking nearly forever to run.  Further investigation
revealed that almost all the time was spent reading the symbol table.

We don't have the same problem on vxWorks/ppc, which uses ELF objects.
Most (all?) of gcc's COFF and ELF targets define DBX_USE_BINCL (c.f.
dbxcoff.h, dbxelf.h) so the linker is able to elide duplicate debug
information.  When I made the same change to the i386-aout target, our
image size shrank from 71 to 31 MB, and gprof was able to complete
it's job in reasonable time.  It seems like defining DBX_USE_BINCL
would be generally useful to those stuck using a.out, at least on 
the most popular targets: x86, m68k, etc.

My question is what is the best way to do this.  I don't know if it's
safe to just define DBX_USE_BINCL (will the extra stabs be ignored on
old (or non-gnu) linkers that don't understand BINCL/EINCL?), or if
separate configs are necessary.  If separate configs are necessary,
should I trigger off --with-gnu-ld?

I'd appreciate any guidance,

        --jtc

-- 
J.T. Conklin
RedBack Networks