Description of problem, bug, incorrect information, or enhancement request: Version of release notes this bug refers to: FC4test3 URL of bug/enhancement (change if different): http://fedoraproject.org/wiki/FedoraDocs/RelNotes/Core4Test3RelNotes
From Ulrich Drepper: As the next step to remove support for the obsolete LinuxThreads library, code compiled and linked on FC4 now automatically uses the NPTL headers and libraries. In previous releases since RHL9 the default was still LinuxThreads since the interface is mostly forward compatible. The advantages of the NPTL interface is that the cancellation handling is faster (when -fexception is used, even in C code) and that the additional interfaces are now available without special compiler and linker parameters (i.e., no -I/usr/include/nptl and -L/usr/lib{,64}/nptl needed anymore). [ lib{,64} is to be interpreted as lib64 on platforms which place DSOs in lib64 directories, and lib otherwise. ] In FC4 it is still possible to create code using the LinuxThreads definitions. For this the linuxthreads-devel package must be installed and -I/usr/include/linuxthreads -L/usr/lib{,64}/linuxthreads must be passed to the compiler. At runtime, it used to be possible to use the LD_ASSUME_KERNEL environment variable to select the appropriate version of glibc and the libpthread DSO. Now it is additionally necessary to specify LD_LIBRARY_PATH=/lib{,64}/obsolete/linuxthreads in the environment since the runtime libraries have also been moved out of the way. There might be the one or the other program which doesn't work at all if the program uses an unfortunate DT_RPATH (which overwrites the LD_LIBRARY_PATH setting). All this makes it more cumbersome to run programs which depend on LinuxThreads. But this is intentional. FC5 will not have LinuxThreads support anymore and all programs have to be converted to use NPTL by then. In general this hasn't been an issue.
In relnotes for FC4test3.