LinuxThreads

The old Pthreads implementation on Linux systems running GNU libc or libc5. It was superseded by NPTL and NGPT, with NPTL becoming the Linux pthreads implementation of record. LinuxThreads is emulated under FreeBSD via the devel/linuxthreads Port. LinuxThreads did not faithfully support the full 1003.1c standard (especially regarding signal handling and PTHREAD_SCOPE_PROCESS), used a control thread, and co-opted two signals (realtime signals if possible, or otherwise SIGUSR1 and SIGUSR2. Realtime signals were supported on Linux 2.2+ when using glibc).

It can still be found here, including the README and a FAQ.