User-level checkpointing through exportable kernel state

Checkpointing, process migration, and similar services need to have access not only to the memory of the constituent processes, but also to the complete state of all kernel provided objects (e.g., threads and ports) involved. Traditionally, a major stumbling block in these operations is acquiring and re-creating the state in the operating system. We have implemented a transparent user-mode checkpointer as an application on our Fluke microkernel. This microkernel consistently and cleanly supports the importing and exporting of fundamental kernel state safely to and from user applications. Implementing a transparent checkpointing facility with this sort of kernel support simplifies the implementation, and expands its flexibility and power.