The Linux Kernel documentation
This is the top level of the kernel's documentation tree. Kernel documentation, like the kernel itself, is very much a work in progress; that is especially true as we work to integrate our many scattered documents into a coherent whole. Please note that improvements to the documentation are welcome; join the linux-doc list at vger.kernel.org if you want to help out.
Licensing documentation
The following describes the license of the Linux kernel source code (GPLv2), how to properly mark the license of individual files in the source tree, as well as links to the full license text.
User-oriented documentation
The following manuals are written for users of the kernel — those who are trying to get it to work optimally on a given system.
Firmware-related documentation
The following holds information on the kernel's expectations regarding the platform firmwares.
Application-developer documentation
The user-space API manual gathers together documents describing aspects of the kernel interface as seen by application developers.
Introduction to kernel development
These manuals contain overall information about how to develop the kernel. The kernel community is quite large, with thousands of developers contributing over the course of a year. As with any large community, knowing how things are done will make the process of getting your changes merged much easier.
Kernel API documentation
These books get into the details of how specific kernel subsystems work from the point of view of a kernel developer. Much of the information here is taken directly from the kernel source, with supplemental material added as needed (or at least as we managed to add it — probably not all that is needed).
Architecture-agnostic documentation
Architecture-specific documentation
Other documentation
There are several unsorted documents that don't seem to fit on other parts of the documentation body, or may require some adjustments and/or conversion to ReStructured Text format, or are simply too old.