Abstract: A technique is provided for facilitating secure operation of an integrated system. The technique includes passing a request for data through a data access controller incorporated within the integrated system, and selectively qualifying the request in accordance with a security state of the controller. The security state of the controller is one state of multiple possible security states, including a null state and a secured state. In the secured state, the controller replaces a standard boot code address associated with a request for boot code with a substitute boot code address. The substitute boot code address addresses an encrypted version of boot code, which is then decrypted by the controller employing a master key set held at the controller. When transitioning to the null state, the master key set is erased.

Abstract: A data authentication technique is provided for a data access control function of an integrated system. The technique includes passing a data request from a functional master of the integrated system through the data access control function, and responsive to the data request, selectively authenticating requested data. The selective authentication, which can occur transparent to the functional master initiating the data request, includes employing integrity value generation on the requested data when originally stored and when retrieved, in combination with encryption and decryption thereof to ensure the authenticity of the requested data. As an enhancement, cascading integrity values may be employed to facilitate data authentication.

Abstract: Techniques are provided for initializing, maintaining, updating and recovering secure operation within an integrated system. The techniques, which employ a data access control function within the integrated system, include authenticating by a current level of software a next level of software within an integrated system. The authenticating occurs before control is passed to the next level of software. Further, an ability of the next level of software to modify an operational characteristic of the integrated system can be selectively limited via the data access control function. Techniques are also provided for initializing secure operation of the integrated system, for migrating data encrypted using a first key set to data encrypted using a second key set, for updating software and keys within the integrated system, and for recovering integrated system functionality following a trigger event.

Abstract: The present invention provides predictable scheduling of programs using a repeating precomputed schedule. In a preferred embodiment, a scheduler accesses an activity scheduling graph. The activity scheduling graph is comprised of nodes each representing a recurring execution interval, and has one root, one or more leaves, and at least one path from the root to each leaf. Each node is on at least one path from the root to a leaf, and the number of times the execution interval represented by each node occurs during the traversal of the graph is equal to the number of paths from the root to a leaf that the node is on. Each node has associated with it an execution interval length, and is adapted to being dedicated to executing the threads of a single activity. The scheduler first selects a current node within the accessed scheduling graph.

Abstract: The present invention provides predictable scheduling of programs using a repeating precomputed schedule. In a preferred embodiment, a scheduler accesses an activity scheduling graph. The activity scheduling graph is comprised of nodes each representing a recurring execution interval, and has one root, one or more leaves, and at least one path from the root to each leaf. Each node is on at least one path from the root to a leaf, and the number of times the execution interval represented by each node occurs during the traversal of the graph is equal to the number of paths from the root to a leaf that the node is on. Each node has associated with it an execution interval length, and is adapted to being dedicated to executing the threads of a single activity. The scheduler first selects a current node within the accessed scheduling graph.