linux call_usermodehelper equivalent in freebsd?

[James Thomason]

>Is there an equivalent in FreeBSD to the Linux kernel function
>'call_usermodehelper' which wraps execve to do as its name 
>suggests, call a user mode helper program?

Andrew, 

It depends on what your user mode helper program is intended to do, 
but the traditional approach is to create a user mode program that 
blocks on a custom system call waiting for an event.  See the 
following 2001 freebsd-hackers thread from Terry Lambert, titled 
"Invoking a userland function from kernel" for further details and 
design considerations:

http://docs.freebsd.org/cgi/mid.cgi?3B646AAB.688669C5

Regards, 
James