LinuxThreads is an POSIX pthreads implementation using "kernel threads".  In
this FreeBSD port, a kernel thread is started using rfork (whereas in the
original Linux implementation a kernel thread is started using the Linux clone
call).
This implementation provides a so-called one-to-one mapping of threads to
kernel schedulable entities. For more information see about the original
LinuxThreads implementation see:

WWW:	http://pauillac.inria.fr/~xleroy/linuxthreads/

Note that LinuxThreads has been integrated with the GNU C library (glibc) since
version 2.0, so the above URL points to dated information.

The complete FreeBSD source code matching the installed userland
must be installed in /usr/src before building linuxthreads.