O'Reilly has published a book for Linux users interested in learning to build their own kernels. Linux Kernel in a Nutshell describes how to build and install Linux 2.6 kernels, starting with downloading the source. It was written by well-known kernel hacker Greg Kroah-Hartman.
I think, this book is a starting point when you would like to learn the Embedded Linux for a Microcontroller, also the Real Time Operating System.
Source: http://oreilly.com/emails/press/9780596100797.html
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