LXR (Linux Cross Reference) is a great source indexing tool, particularly useful for big projects like the Linux kernel.

Here are Internet sites that make it easy to explore the Linux sources thanks to the LXR engine:

• lxr.free-electrons.com
  At last, an up to date LXR site with an easy to remember URL!
• linux-m32r.org
• Coywolf
• LXR
  The original site.

Please let us know if you know about other LXR sites!

You can also browse Linus Torvalds' GIT tree.

For browsing documentation included in the kernel sources, you may prefer our kernel documentation pages, in which DocBook files have been converted to HTML.