International Business Machines Corporation

Brian B Moore

David Arlen Elko

Michael D Swanson

John F Isenberg, Jr

Jeffrey Mark Nick

Jeffrey Alan Frey

Audrey A Helffrich

Greg A Dyck

Jimmy Paul Strickland

David E Lee

Joseph A Williams

Gregory A Burke

Timothy John Slegel

David Harold Surman

Mark Anthony Check

Michael Howard Hartung

John Ted Rodell

Allan Samuel Meritt

William Augustus Carter

Kenneth R Lynch

William C Shepard

Kevin F Smith

Carl Zeitler, Jr

Arthur J Sutton

Roger L Cormier

John D Rotramel

Howard Loomis Page

George W Wang

David H Wansor

John L Burk

Ray A Larner

Leslie Charles Balfour

Paul Emile Boudreau

Gary V Railsback

Donald J Lucas

Jeff D Vowell

Steven J Repka

Jeffery M Mick

Jeffery M Nick

John F Isenberg

Object-code instruction traces are employed to analyze selected instructions of a year-2000 (Y2K) remediated application program for possible remediation failure when confronted by a year-2000 date. The analysis includes directly identifying one or more instructions of the remediated application program that may fail. A remediation-failure-pattern descriptor is assigned to each examined instruction which is indicative of whether the remediated instruction may fail when confronted by a date in the year-2000 range. The analysis employs user-specifiable run-control values, as well as predetermined filter-specification values in comparing traces of each selected object-code instruction to predefined remediation-failure patterns.

Method and apparatus for identifying remediation failures in year-2000 remediation programs

A computer architecture that provides the definition of a 20 bit signed displacement value used to form the operand storage address.

Computer instructions for having extended signed displacement fields for finding instruction operands

A method and apparatus for runtime remediation of object-code instructions (such as date instructions that are not year 2000 compliant) in a computer program. Before runtime, a setup function of a program monitor locates each instruction to be remediated in a load module of a user program and overlays the instruction with a trap instruction. The address of the overlaid instruction is stored in a scan slot of a window control table (WCT). The text of the overlaid instruction is stored in a corresponding operand slot of the WCT along with control information including a set of flags and windowing and cycling parameters. At runtime, upon decoding a trap instruction, the CPU transfers control to an instruction simulation function of the program monitor, which searches the scan slots of the WCT for the one containing the address of the overlaid instruction. Upon finding the scan slot, the instruction simulation function performs an instruction simulation operation in accordance with the control information in the corresponding operand slot, then returns control to the user program. If an execute flag is not set, the instruction simulation function invokes a specified user routine without executing the overlaid instruction. If the execute flag is set, the instruction simulation function executes the overlaid instruction in a mode of operation determined by the remaining flags. In a windowing mode, one or both instruction operands are compared with a specified delimiter, and the instruction is executed as though a specified increment were added to the operand before performing the operation of the instruction if the operand is less than the delimiter. In a cycling mode, a specified increment is added to the result the instruction would otherwise produce if that result is less than zero.

Method and apparatus for runtime remediation of object-code instructions in a computer program

A central processing unit of an information handling system is provided with a Trap instruction to facilitate transfer of control from a user program to a trap program. A dispatchable unit control block (DUCT) of the CPU is loaded with the address of a trap control block, which in turn contains the addresses of a trap save area and a trap program. The user program is provided with Trap instructions at the desired transfer points. Upon decoding a Trap instruction in the user program, the CPU saves state information from the program status word (PSW), general registers and access registers in the designated trap save area, loads the address of the trap control block into a general register, and copies the address of the trap program into the instruction address field of the PSW to transfer control to the trap program. Upon completion of execution, the trap program may issue a Resume Program (RP) instruction to restore the previously saved state information to return control to the user program.

Method and apparatus for performing a trap operation in an information handling system

Object-code instruction traces are employed to analyze selected instructions of an application program for possible failure when confronted by a year-2000 date. The analysis includes directly identifying one or more instructions of the application program that may fail, as well as identifying whether the one or more instructions have a characteristic of a predefined false-positive failure pattern. A failure-pattern descriptor is assigned to each examined instruction which is indicative of whether the instruction may fail when confronted by a date in the year-2000 range, and whether the instruction is a possible false-positive failing instruction. The analysis employs user-specifiable run-control values, as well as predetermined filter-specification values in comparing traces of each selected object-code instruction to predefined instruction failure patterns.

System for predicting year-2000 instruction failures

Predicting year-2000 instruction failures

A method, apparatus, and article for solving the year 2000 problem involve processing a computer object program to identify object code instructions referencing date information for an operation which involves more than one century. The object code is altered by altering each identified instruction with an instruction to effect a transfer of control to a Year 2000 routine. The Year 2000 routine is a routine for altering the execution of an identified instruction in accordance with the Year 2000 routine and thereafter returning control to the object code.

Identifying date fields for runtime year 2000 system solution process, method and article of manufacture

Method for predicting year-2000 instruction failures

A Structured External Storage (SES) processor is linked by a communication means to one or more general purpose processors. Two or more applications executing on the one or more general purpose processors communicate function request messages to a message processor within the SES to effect serialized sharing of data within the SES. Within the message processor, a predicate function means executes unconditionally on receipt of one of the function request messages, and a data function means executes conditionally and atomically with respect to the predicate function means following a 'successful' condition produced by the predicate function means. The predicate function means comprises a predicate compare function means and a predicate update means, the predicate compare function means executing unconditionally and producing a 'successful' or 'unsuccessful' result, the predicate means executing conditionally and atomically with respect to the predicate compare function means, following a 'successful' result by the predicate update compare function means.

Method and apparatus for performing conditional operations on externally

A mechanism for communicating messages, each including a command and a response, in a network having central processing complexes (CPCs) and one or more coupling facilities. Each coupling facility has a central processor for executing instructions and a main storage. Messages are sent from a message control block in the main storage of the CPC sending the message, and the response to the message is received in a message response block of the CPC without an interrupt to the program being executed by the central processor of the CPC. Each message from a CPC to the coupling facility may include a command and an indicator bit which instructs the coupling facility to execute the command either in synchronism with or asynchronously to the execution of the sending processor. The coupling facility executes the command and returns a response which is received in a message response block of the main storage of the sending CPC without an interrupt to any program being executed by the central processor of that CPC.

In a multiprocessing system having a coupling facility, communicating

A message path mechanism in a network having central processing complexes (CPCs) joined by message paths to a coupling facility. The coupling facility locates message paths for sending messages from one CPC to another and for sending messages between the coupling facility and one or more of the CPCs. A message path status table is provided having an entry for each of the message paths. Each entry has an indicator indicating whether its message path is active or inactive. multiple connections between the coupling facility and systems in the CPCs are registered in the coupling facility. Also provided is a mechanism for validating that each message path is connected properly such that if a message path is disconnected and then reconnected to a CPC, the validation mechanism insures that the message path has been reconnected correctly.

Coupling facility for receiving commands from plurality of hosts for

Storage is managed in a shared electronic store (SES) by assigning storage classes (STCs) to each directory entry having a data item stored in SES. The assignments of directory entries and data elements to the respective STCs can be changed at any time by any CPC. Eventually, no free space remains in the SES cache, and then space for new directory entries and data items must be obtained by reclaiming space occupied by directory entries and associated unchanged data items. The reclaiming of SES space is controlled on a STC basis. Any specified STC may reclaim from itself or from another STC using reclaiming software/microcode in SES, which includes a reclaim vector, a reclaim counter, a queue, and reclaiming controls. The vector and counter have respective elements for all possible STCs to controls how a specified STC may reclaim space from any or all target STC. Any enabled target STC reclaims its space according to an LRU algorithm maintained by a queue for the STC. A CPC can issue a command to load different values in target STC elements in the SES vector for a specified STC to control how reclaiming is apportioned for the specified STC. In SES, associated target counter elements are loaded from its vector. Reclaiming is done automatically in SES upon each directory miss in the current target STC having a non-zero counter value, when no free space exists. The counter is decremented for each reclaimed directory entry until its count reaches zero, and then the counter element for the next non-zero target STC is used for reclaiming until it reaches zero. When all STC elements in the counter are zero for the specified STC, the counter elements are reloaded from the vector elements to repeat the reclaiming operation, as long as a repeat factor for the specified STC has not reached zero. The repeat factor is decremented each time the counters are loaded from the vector. When the counters and repeat factor have all reached zero, reclaiming is disabled for the specified STC.

Software cache management of a shared electronic store in a supplex

In a multi-system complex having central processing complexes (CPCs) and subsystems, a hardware facility for prompt interdicting I/O and message operations. A CPC or subsystem failure causes as interruption in the availability of the data bases to the attached network of terminals. Often such networks have thousands of terminals. Even a short loss of data is detrimental. Therefore the CPC or subsystem takeover must be accomplished as quickly as possible and the I/O attached to the failing CPC or subsystem must be interdicting to release it for use to the rest of the complex. The disclosed hardware facility provides a mechanism which is program initiated and controlled and which guarantees the prompt completion of the interdiction function.

Interdicting I/O and messaging operations from sending central

A shared coupling facility contains system lock management (SLM) means for supporting a distributed locking protocol used by a plurality of sharing lock managers each executing on a processor having access to the shared memory and to any other processors in the processor complex. A request to lock a resource shared among the lock managers is first checked against a local hash table and then, if necessary, forwarded to the system lock management means in the shared memory for synchronous or asynchronous processing. List structures are maintained in the shared coupling facility to support the protocol, and are used by the system lock management means to record data recovery status. The sharing lock managers interact with the SLM means to control/manage lock contention, waiter queueing, and compatibility processing.

Method and apparatus for distributed locking of shared data, employing a

A Structured External Storage (SES) device/processor is connected to two or more DP systems, thereby loosely coupling the systems. The SES is capable of holding data objects of two distinct types (List objects and Cache objects), and communicates commands and command responses with the systems using a message protocol. A support facility within a processor on which a system is executing receives status indications from the SES without interrupting mainline system execution. Within the SES, a serialization mechanism allows more than one command to execute in parallel without loss of data object integrity, or command consistency. A forward completion mechanism sends to systems early notification of completion of certain commands, without permitting results inconsistent with this notification to be obtained by the systems. And a restart mechanism permits interrupted commands to be restarted by the initiating system or, in certain cases, by another system.

Method and apparatus for coupling data processing systems

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Poughkeepsie, NY, United States of America

Brian B Moore