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Dynamic Debugging

IP.com Disclosure Number: IPCOM000078726D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Perry, TJ: AUTHOR

Abstract

Program Event Recording (PER) hardware on S/370 Relocate machines provides for program interrupts on four types of events - successful branching, instruction execution, general register alteration, and storage alteration. The Dynamic Support System (DSS) allows a user to debug with the aid of this hardware. The user can specify the action to be taken (such as a snapshot dump or a DSS command statement) or be executed when one or more events occur within a given range. The hardware provides the range for two types of events (instruction execution and storage alteration), while the DSS software simulates the range facility for the other two (branching and register alteration).

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Dynamic Debugging

Program Event Recording (PER) hardware on S/370 Relocate machines provides for program interrupts on four types of events - successful branching, instruction execution, general register alteration, and storage alteration. The Dynamic Support System (DSS) allows a user to debug with the aid of this hardware. The user can specify the action to be taken (such as a snapshot dump or a DSS command statement) or be executed when one or more events occur within a given range. The hardware provides the range for two types of events (instruction execution and storage alteration), while the DSS software simulates the range facility for the other two (branching and register alteration).

This is done by monitoring for instruction execution when outside the range and then, when an interrupt indicates the range has been entered, monitoring for the events for which the hardware does not provide a range. If, subsequently, control passes outside the range and an even occurs, the software will ignore the event and reestablish simulation of the range until the range is entered again.

Two System/370 instructions - MOVE LONG and COMPARE LONG - are interruptible; they may cause redundant PER events. For instance, if a MOVE LONG instruction is interrupted, the PSW (Program Status Word) address will not have been incremented and will still point to this instruction. The PER hardware may indicate the instruction execution, register alteration, or storage alteration event...