International Business Machines Corporation

George H Bean

Peter H Gum

Mark S Farrell

Leslie W Wyman

Casper A Scalzi

Roger E Hough

Donald W McCauley

Terry L Borden

Francis E Johnson

John Fenton Scanlon

John C Rathjen, Jr

Mark E Rakhmilevich

Donald W Mccauley

John C Rathjen

John F Scanlon

The embodiment discloses a method and means for partitioning the resources in a data processing system into a plurality of logical partitions. Host control code may be embodied in programming, microcode, or by special hardware to enable highly efficient operation of a plurality of preferred guest programming systems in the different partitions of the system. The main storage, expanded storage, the channel, and subchannel resources of a system are assigned to the different logical partitions in the system to enable a plurality of preferred guest programming systems to run simultaneously in the different partitions. This invention automatically relocates the absolute addresses of the I/O channel and subchannel resources in the system to their assigned partitions. Also the absolute and virtual addresses of the different guest programming systems are relocated into, as well as page addresses for any expanded storage, their assigned partitions. The guest programming systems generally will be different operating systems. The logical CPU(s) of the guests are dispatched on one or plural real CPUs in the system using the S/370XA SIE (start interpretive execution) instruction. Special operations are provided, including the CPU alerting of other guests in different partitions using I/O interruption signalling. Interception is provided to handle special circumstances.

Logical resource partitioning of a data processing system

The embodiment obtains rapid switching between system control programs (SCPs) by switching an address in a prefix register in a CPU of a MP or UP data processing system from a guest SCP's PSA (program save area) to a host SCP's PSA by fetching the host prefix value from a predetermined control block in main storage. The prefix register loading changes the control of the CPU from a preferred guest SCP to a host SCP. This SCP switching is done by hardware and/or microcode means in the CPU. It further detects preset states in the CPU that enable a rapid determination of which SCP is to handle a sensed event, permitting the guest SCP to immediately handle events predetermined to belong to the guest. This manner of CPU control obtains for a preferred guest SCP (such as MVS/370) operating under a host SCP (such as VM/370) nearly the efficiency of standalone execution on the CPU by the preferred guest SCP.

Method and means for switching system control of CPUs

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Hyde Park, NY, United States of America

George H Bean