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Exceptions to these rules may be granted for academic purposes: Write
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All source code in The Linux Kernel Hackers' Guide is placed under
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for a copy of the GNU ``GPL.'' Source code for all full example programs is
available on-line as tsx-11.mit.edu:/pub/linux/docs/hacker-source.tar.Z
and a copy of the GPL is available in that file as COPYING.
[O.K., so it will be available when there is some
source to distribute...]
UNIX is a trademark of X/Open
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Linux is not a trademark, and has no connection to
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If any trademarks have been unintentionally unacknowledged, please
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The The Linux Kernel Hackers' Guide is inspired by all of us ``kernel hacker wannabees'' who
just did not know enough about unix systems to hack the Linux kernel
when it first came out, and had to learn slowly. This guide is
designed to help you get up to speed on the concepts that are not
intuitively obvious, and to document the internal structures of
Linux so that you don't have to read the whole kernel source to
figure out what is happening with one variable, or to discover the
purpose of one function call.
Why Linux? Well, Linux is the first free unix clone for the 386 to
be freely available. It is a complete re-write, and has been kept
small, so it does not have a lot of the time-honored baggage that
other free operating systems (like 386BSD) carry, and so is easier to
understand and modify.
Unix has been around for over twenty years, but only in the last few
years have microcomputers become powerful enough to run a modern
protected, multiuser, multitasking operating system. Furthermore, unix
implementations have not been free. Because of this, very little free
documentation has been written, at least for the kernel internals.
Unix, though simple at first, has grown more and more appendages, and has
become a very complex system, which only ``wizards'' understand. With
, however, we have a chance to change this, for a few reasons:
Linux has a simple kernel, with well-structured interfaces.
One person, Linus Torvalds, has control of what code is added to
, and he does this work gratis. This means that random pieces
of code are not forced into the kernel by some company's politics, and
the kernel interfaces stay relatively clean.
The source is free, so many people can study it and learn to
understand it, becoming ``wizards'' in their own right, and eventually
contribute code to the effort.
It is our hope that this book will help the nascent kernel hacker
learn how to hack the Linux kernel, by giving an understanding of
how the kernel is structured.
of course, for starting this whole time
sink, and for gently providing explanations whenever necessary. He
has done a wonderful job of keeping the kernel source code
understandable and neat. I can't imagine having learned so much in
the past few years without .
Krishna Balasubramanian and Douglas Johnson,
for writing much of the section on memory management, and helping
with the rest.
for helping document the system call interface.
for writing the section on how to write a
SCSI device driver.
for the review of Writing UNIX
Device Drivers and for his help with the section on writing device
for providing me with a Linux-related
job, and for allowing me to do work on the KHG on their time.
Kim Johnson, my wife,
for tolerating and
encouraging me even when I spend my time on crazy stuff like Linux.
If you wish to make a derived work, please start
from the original document. To do so, please contact
Rickard E. Faith, firstname.lastname@example.org. The original is available
for anonymous ftp as ftp.cs.unc.edu:/pub/faith/papers/scsi.paper.tar.gz.