>Didn't you know?  We already do.  8-)

No, I didn't. I went looking for the emuls line that'd put both a.out
and elf backends into gas and ld, not just libbfd.  I dont see them.
them. look at, say, gas.new/arch/sparc/Makefile.inc: it pulls in
obj-aout.c or obj-elf.c, but not both.

The mips backends for gas seems able to do either, tho' I confess I
havent tried as --emul in ages. Is that mips-specific?