ld option -rdynamic not documented

[Peter Eisentraut]

I'm trying out the glibc feature to print backtraces from the program,
as described at
<http://www.gnu.org/software/libc/manual/html_node/Backtraces.html>.
There, it says

"""
Currently, the function name and offset only be obtained on systems that
use the ELF binary format for programs and libraries. On other systems,
only the hexadecimal return address will be present. Also, you may need
to pass additional flags to the linker to make the function names
available to the program. (For example, on systems using GNU ld, you
must pass (-rdynamic.)
"""

This works, in fact, but the option -rdynamic is not documented.  I
understand that GNU ld supports a whole host of legacy and compatibility
options, but in case you don't want to document it, could you point out
what the canonical option name is in your opinion so the glibc manual
could be adjusted?