Just reading about this...turns out nommu Linux can use vfork(), which unlike fork() shares the parent's address space. Another drawback is that vfork's parent process gets suspended until the child exits or calls execve().
Typicall you always call vfork() + execve(), vfork is pretty useless on its own.
Think about it like CreateProcess() on Windows. Windows is another operating system which doesn't support fork(). (Cygwin did unholy things to make it work anyway, IIRC.)
