A Word About Kernel Trees
Linux development takes place in many different places, geographically and organizationally. “Official” development takes place in Linus’s tree (a “tree” being a source code repository), which is available on kernel.org. Since it can be difficult to get Linus’s attention, usually Linus’s tree is at least a little out-of-date in almost all projects (which can be a good thing, since that implies the code that does make it in is more mature).
In that past, it could be quite difficult to get code into the official tree, so PowerPC-specific work took place in PowerPC trees and was occasionally submitted upstream. Support for cutting-edge hardware would typically only be found in the cutting-edge PowerPC development trees, and only show up in official trees after a while.
However, these days it is much easier to get code into Linus’s tree, and the fact that Linus uses an Apple G5 means he tends to be more interested in PowerPC patches. So current work is sent directly to Linus and the official trees. Since the need for PowerPC-specific trees is not as great as it was, they are being phased out.
PowerPC Kernel Source for Users
Users wanting the latest working PPC kernel should first use their distributions’ source packages. Distributions apply many fixes and enhancements to their kernels.
If the distribution does not offer some required feature or fix, visit kernel.org.
PowerPC Kernel Source for Developers
Developers should work directly with the official kernel.org trees and submit code directly to those tree maintainers.
Historical PowerPC Trees
BitKeeper is a proprietary source control system that was used for PowerPC kernel source and later for official kernel source, before being replaced by git. To access the historic (2.4 through early 2.6) PowerPC Linux kernel trees, visit the Bitkeeper web site.