Browse Prior Art Database

Reproduction of System Infinite Loops

IP.com Disclosure Number: IPCOM000102146D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Corrigan, MJ: AUTHOR [+3]

Abstract

A method is described to allow dynamic debug of a computer system which was executing an infinite loop after the computer system had been restarted.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Reproduction of System Infinite Loops

       A method is described to allow dynamic debug of a
computer system which was executing an infinite loop after the
computer system had been restarted.

      When a computer system fails due to an infinite loop in low
level software, such that it cannot be interrupted, a common debug
technique is to initiate a Main Storage Dump. A main store dump is a
complete copy of main volatile storage at some instant in time.

      When a loop condition exists, the dump can be used to examine
what caused the loop not to terminate.  This can be done by trying to
analyze the dump, to try to determine what instructions had been
executed prior to the dump, and/or trying to determine what
instructions would have been executed next if the dump had not been
taken.  This process is very difficult and time consuming.

      Three tools are actually involved.  First, a DumpViewer is used
to load the main store dump from a customer-supplied tape onto an IBM
System/370* (or other large) system.  The DumpViewer allows the dump
data to be viewed.  Second, a Simulator, a processor instruction set
simulator which runs on IBM PC or PS/2* is used to simulate the
instruction set of the processor.  Finally, DataCapture, is also
running on the IBM PC or PS/2 is used to capture data from the main
storage dump and pass it to the Simulator.  The Simulator is able to
continue the actual instruction execution of the loop condition
EXACTLY as it...