Sources of information about the Linux kernel:

• Linux kernel site
  • The Linux Kernel documentation
  • https://www.spinics.net/lists/linux-doc/
• https://github.com/linux-test-project/ltp/
• Kernel Hackers Manual, man 9
• kernelnewbies.org - information for (beginning) Linux kernel developers
  • http://kernelnewbies.org/LinuxChanges
  • http://lists.kernelnewbies.org/pipermail/kernelnewbies/
• Kernel coverage at LWN.net
• Email lists for Linux kernel developers
• Linux Kernel Teaching, linux-kernel-labs
• https://www.opensourceforu.com/tag/linux-device-drivers-series/
• https://sysplay.github.io/books/LinuxDrivers/book/
• linux-insides

Documentation and articles:

• https://makelinux.github.io/kernel/map/
• https://makelinux.github.io/kernel/diagram/

Other:

• Linux Driver Template

Embedded Linux references—using Linux in an embedded system:

• Embedded Systems/Linux
• "Flash Filesystems for Embedded Linux Systems" by Cliff Brake
• "Embedded Linux: Hardware, Software, and Interfacing" book by Craig Hollabaugh
• "Embedded Linux" book by John Lombardo
• "Embedded Linux Primer" book by Christopher Hallinan

Historical:

• The Linux Kernel HOWTO (2003) by Alavoor Vasudevan
• KernelAnalysis-HOWTO (2003) by Roberto Arcomano
• http://tldp.org/HOWTO/HOWTO-INDEX/os.html#OSKERNEL
• Linux Technology Reference

Historical books:

• Linux Kernel Development, 3rd Edition (2010) by Robert Love
• Understanding the Linux Kernel, Third Edition (2005) by by Daniel P. Bovet and Marco Cesati - Table of Contents
• Linux Device Drivers, Third Edition (2005) by Jonathan Corbet, Alessandro Rubini, and Greg Kroah-Hartman - Available in PDF format under a Creative Commons Attribution-ShareAlike 2.0 license
• Linux Kernel 2.4 Internals (2002) by Tigran Aivazian - Under GPL license
• The Linux Kernel 2.0.33 (1999) by David A Rusling
• "Flash Filesystems for Embedded Linux Systems" by Cliff Brake and Jeff Sutherland

Linux kernel based projects:

• w:UClinux
• w:KGDB