International Business Machines Corporation

Suzanne M John

Roger E Hough

Kenneth J Oakes

Leslie W Wyman

Marten J Halma

Kenneth J Fredericks

Robert Edward Galbraith

James C Mazurowski

James Edward Bostick

Jeffrey Paul Kubala

Allan Samuel Meritt

Joseph C Elliott

Martin W Sachs

Charles E Shapley

David E Stucki

Richard Roland Guyette

Frank W Brice

Richard Cwiakala

Ira Glenn Siegel

Assaf Marron

John C Rathjen, Jr

David W Hollar

Paul A Malinowski

Norman Ehsan Shafa

Karen M Noonan

Miriam P Brown

Enables any OS of plural OSs within any of plural logical-resource partitions (LPARs) of a CEC to use interpretive execution for synchronously-executable CHSC (channel subsystem call) commands. A CHSC command authorization mask (CCAM) is provided to control which CHSC commands are allowed to execute interpretively (with pass-through), and which commands are executed with hypervisor intervention (as all prior CHSC commands did). By enabling interpretive execution of those commands which can successfully operate with pass-through, significant system efficiency is obtained. And by disabling interpretive execution for a subset of CHSC commands (which are not allowed to execute with pass-through) potential system failures may be prevented. Thus, interpretive execution may be restricted differently among the OSs in a CEC. Novel CHSC command execution now handles multiple images of shared I/O resources by use of image identifiers, which could not be done before. The information requested by any OS issuing a CHSC command is filtered and optionally compacted by the I/O subsystem responding to the command by only providing information obtained from control blocks associated with the OS which issued the command. This is done by having a set of control blocks for each I/O resource, each control block in the set being associated with a particular OS.

Pass-through for I/O channel subsystem call instructions for accessing

This invention involves reconfiguration support for shared I/O resources in a a computer electronic complex (CEC) supporting both shared and unshared I/O channels of the type described and claimed in U.S. patent application Ser. No. 07/898,867 (PO9-92-016) filed on the same day as the subject application and assigned to the same assignee as the subject application. Prior channel subsystem call (CHSC) instructions cannot execute when a channel is to be configured as shareable by plural operating systems in a CEC.

Asynchronous command support for shared channels for a computer complex

Provides a method for increasing the connectivity of I/O resources to a multiplicity of operating systems (OSs) running in different resource partitions of a computer electronic complex (CEC) to obtain sharing of the I/O resources among the OSs of the CEC, including channels, subchannels (devices), and control units (CUs). The invention provides image identifiers (IIDs) for assigning resources to the different OSs. Each shared I/O resource has a sharing set of control blocks (CBs) in which a respective CB is assigned to (and located by) a respective IID of one of the OSs. Each of the CBs in a sharing set provides a different image of the same I/O resource. The different CB images are independently set to different states by I/O operations for the different OSs, so that the OSs can independently share the same I/O resource.

Method and means for sharing I/O resources by a plurality of operating

A request is made by a system in a first logical partition, within a logically partitioned data processing system, to dynamically change the I/O configuration of the host system in a way that affects a system in a second logical partition. The hypervisor intercepts the request, ensures the serialization of such dynamic I/O requests, and allows dynamic reconfiguration to proceed. Subsequently, the hypervisor determines the effect of the reconfiguration on the second partition, and notifies the second partition of the change.

Method and apparatus for dynamically changing the configuration of a

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Poughkeepsie, NY, United States of America

Suzanne M John