Unfortunately, the code for the native MIDI support on Linux is derived
from source under the GNU General Public License, and not the GNU LGPL.
Therefore, it's not built by default.

Native Midi support for Linux should work on FreeBSD too ( I can not test it ).

Midi device can be selected with enviroment variable SDL_NATIVE_MUSIC, it can be
one of following values: 
GUS  - GravisUltrasound
AWE  - SoundBlaster AWE32
FM   - FreqentionModulation SoundBlaster Compatible
OPL3 - Yamaha OPL/3
EXT  - External MIDI port

External MIDI port can be set with env. SDL_NATIVE_MUSIC_EXT (SDL_NATIVE_MUSIC_EXT="1").

Autoselect priority:
1. GUS
2. AWE
3. use Timidity
4. FM
5. EXT

Also if you want use FM befor Timidity set variable SDL_NATIVE_MUSIC="FM" or edit
source code native_midi_lnx.c( return value in function synth_setup, by autoselect
FM should return 1).
For using FM: files drums.sb drums.o3 std.sb std.o3 should be moved to /etc/ dir
( or symlink created ).