... and earlier versions of the kernel is in the data types used for the start and len arguments. Whereas new kernels always use unsigned long, older kernels used shorter types. This change has ... memory pages, because a user-space program depends on a lot of library code. mlock, too, is limited to privileged users. The most important devices can't be handled in user space, including, ... arbitration of the mouse device between clients, so that several mouse-sensitive applications can run on different virtual consoles. Sometimes, though, the user-space driver grants device access...