* These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. * These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread_create, crypt, login, exit and more.

musl provides consistent quality and implementation behavior from tiny embedded systems to full-fledged servers. Designed from the ground up for static linking, musl carefully avoids pulling in large amounts of code or data that the application will not use. Dynamic linking is also efficient; by integrating the entire standard library implementation, including threads, math, and even the dynamic linker itself into a single shared object, most of the startup time and memory overhead of dynamic linking have been eliminated. musl features the first post-NPTL implementation of POSIX threads for Linux, and the first aimed at complete conformance and robustness. Thread cancellation has been re-designed to avoid serious race conditions in the original NPTL design. As for efficiency, the whole threads implementation weighs in at around 10-20k depending on target architecture and compiler settings.