FreedomHEC is the hardware "unconference" organized by Linux developers to educate and encourage hardware developers about making their hardware compatible with Linux and other free operating systems. For those not in attendance, the DDK can be downloaded from Kroah-Hartman's site at kernel.org.
Kroah-Hartman is the current maintainer for USB and PCI device driver code for the Linux kernel, one of the stable kernel maintainers, and one of the co-authors of the book Linux Device Drivers, Third Edition, a complete copy of which is included in PDF form in the kit.
The kit also includes complete kernel source for the latest stable release, version 18.104.22.168, and an extensive collection of documentation and support files. The documentation includes HOWTOs and instructional texts, API and compatibility references, DocBook templates, recommended procedures for submitting and patching device drivers, and a library of architecture- and device-specific technical references.
Kroah-Hartman describes the kit in his initial announcement as the first "proper" device driver development kit for Linux, and notes his intention to expand on it in the future, inviting contributions and pointers. The CD image is licensed under the GNU General Public License for free redistribution.