"Over time, the Linux kernel has become efficient in
terms of both memory and CPU usage, as well as extremely stable.
But the most interesting aspect of Linux, given its size and
complexity, is its portability. Linux can be compiled to run on a
huge number of processors and platforms with different
architectural constraints and needs. One example is the ability for
Linux to run on a process with a memory management unit (MMU), as
well as those that provide no MMU. The uClinux port of the Linux
kernel provides for non-MMU support."