DynAMOS is an on-the-fly kernel updating system that enables commodity operating systems to gain adaptive and mutative capabilities without kernel source recompilation or reboot. It employs a novel and efficient dynamic instrumentation technique called adaptive function cloning. Execution flow can be switched adaptively among multiple editions of functions, possibly concurrently running. This approach becomes the foundation for dynamic replacement of non-quiescent kernel subsystems when the timeliness of an update depends on synchronization of multiple kernel paths.
Updates of non-quiescent subsystems. It accomplishes substantial updates of core kernel subsystems that never quiesce, such as the scheduler and kernel threads.
Datatype updates. It offers a technique for updating compact datatype definitions. Additions of new fields in a datatype is supported using a shadow data structure containing the fields.
Safe reversibility. A methodology of quiescence detection is employed. Updated functions can be removed with the guarantee that they are not used by the stack or program counter of any process.
Adaptability. Execution can be switched adaptively between multiple, possibly concurrently running, function editions. This is the first dynamically applied, adaptive kernel updating system.
Synchronized updates. A multi-phase updating algorithm for replacement of complete kernel subsystems is offered. Notably, for the cases where the timeliness of an update depends on synchronization of multiple kernel paths.