Missing system call in linux emulation

[Steven Hartland]

When running the BattleField 1942 server under FreeBSD
5.0-RELEASE / 5.1-RELEASE I get the following
when the server terminates or changes map ( which I
understand forks exec's then parent quits )

Core was generated by `bf1942_lnxded.stati'.
Program terminated with signal 12, Bad system call.
#0  0x086cc7cf in _exit ()
(gdb) bt 
#0  0x086cc7cf in _exit ()
#1  0x08695a2f in __pthread_manager ()

Running under truss I get:
write(56,0xbfbff8e0,148)                         = 148 (0x94)
linux_rt_sigprocmask(0x2,0x0,0xbfbff840,0x8)     = 0 (0x0)
SIGNAL 32
linux_rt_sigsuspend(0xbfbff840,0x8)              ERR#4 'Interrupted system call'
SIGNAL 32
SIGNAL 32
linux_sigreturn(0xbfbff54c)                      ERR#4 'Interrupted system call'
SIGNAL 20
linux_wait4(0x12421,0x0,0x80000000,0x0)          = 74785 (0x12421)
-- UNKNOWN SYSCALL 252 --
(null)()                                         ERR#78 'Function not implemented'
SIGNAL 12
SIGNAL 12
Process stopped because of:  16
process exit, rval = 140

Any one know how I can track down what function is missing and hence
look at fixing it?
    
    Steve