I need to port some of my stuff to NPTL and I'm trying to confirm what I have been reading on the web. Although the following read like statements, they are really questions. (1) SL3x supports nptl: nptl was back-ported into the 2.4 kernels. glibc is still LinuxThreads. You need to link with the nptl libraries from nptl-devel. (2) SL4x supports nptl natively: 2.6 kernels support nptl. No back-port needed. glibc's pthreads is nptl as in the nptl-devel rpm. No need to link with nptl-devel libraries. Thanks!