How to build std_xrxhb_xtx.rbf from uhd fpga source

Hi all,
I compile the uhd fpga source then produce rbf like that: usrp_std.rbf.
I don’t know how many rx and tx this rbf can support. I guess the count
of rx and tx it support is in some configure file. so how to config it
if I
want
to build a 2rx and 2tx rbf? And I also need this config for inband
world.

Thanks!