redhat man page for break

UNIMPLEMENTED(2)					     Linux Programmer's Manual						  UNIMPLEMENTED(2)

NAME
       afs_syscall, break, ftime, gtty, lock, mpx, phys, prof, profil, stty, ulimit - unimplemented system calls

SYNOPSIS
       Unimplemented system calls.

DESCRIPTION
       These system calls are not implemented in the Linux 2.0 kernel.

RETURN VALUE
       These system calls always return -1 and set errno to ENOSYS.

NOTES
       Note that ftime(3), profil(3) and ulimit(3) are implemented as library functions.

       Some system calls, like ioperm(2), iopl(2), ptrace(2) and vm86(2) only exist on certain architectures.

       Some system calls, like ipc(2) and {create,init,delete}_module(2) only exist when the Linux kernel was built with support for them.

SEE ALSO
       obsolete(2)

Linux 2.0							    1998-06-12							  UNIMPLEMENTED(2)