Does anyone know any good resources for detailed (but introductory)
information about any of the BSD kernels, the Linux kernel (2.6+), or the
Darwin kernel? Any books on basic kernel design and concepts would be
helpful as well. Printed resources are preferable to online ones (if I'm
going to read technical documents and information for an hour or two every
day for a few weeks, I'd much rather be able to do it on my couch, under a
lamp, than staring at a screen until my neck cramps [that rhyme was
unintentional]).

Thanks in advance!

--Patrick C.