The IcedTea project, historically, had a lot of changes in it compared to vanilla OpenJDK 6 source code. The number of changes went down eventually, as some of them were included in the main OpenJDK 6 source tree. Some of the changes, such as NIO2 API support (taken from OpenJDK 7), were experimental and were removed.

The changes are stored in the IcedTea source tree in the form of patches (different files) and not as changesets in a separate branch. This can confuse users who are not experienced with class Unix/Linux patch techniques and tools. The different files are stored in the patches directory and are applied to the OpenJDK source tree during the configure build step.

Contrary to OpenJDK 8, the GNU Autoconf build system is not integrated tightly into the IcedTea build process. The Autoconf configure step prepares the environment for building the OpenJDK sources and the standard (slightly patched) OpenJDK makefiles are run on the Autoconf make step.

In this recipe,...