How to pass a command to simulator through GDB

[ligang@sunnorth.com.cn]

Hi,

I am running GDB Dejagnu testsuite.
I want to pass a command （sim mac）to simulator through GDB which is like 
the following function:

(gdb) target sim
Connected to the simulator.
(gdb) sim mac

I add one line in the baseboard file ---- set_board_info 
gdb,target_sim_options "mac".
But, it will work as "(gdb) target sim mac" which don't work like above.

What should i do?

Best regards
                     Ligang