The unwanted function was a string printf formatting function that was part of XDC. One of the SYS/BIOS folks helped me disable the feature that was including it.
Using nm or objdump to search for symbol reference can be tricky if the referring function is not, itself, referenced (and each function is in its own section...).
Maybe in a future version we can add a command line switch to the linker to have it dump dependency chains for each symbol in the map file. :)
Thanks!