Browse Prior Art Database

Halt/ Reset Option in Non-maskable Interrupt Handler

IP.com Disclosure Number: IPCOM000121754D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Jones, CW: AUTHOR [+2]

Abstract

This article describes a technique for application program interface to designate computer system action in the event of a catastrophic error reported via non-maskable interrupt.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Halt/ Reset Option in Non-maskable Interrupt Handler

      This article describes a technique for application
program interface to designate computer system action in the event of
a catastrophic error reported via non-maskable interrupt.

      On most microprocessor-based systems, a catastrophic error
results in a non-maskable interrupt (NMI) which halts the system.
Aside from a number on the display, no other information is provided
and all information is lost when power is removed.  A system which
supports unattended operation needs a way for software to log and
react to catastrophic errors.  It cannot depend upon a display that
may or may not be present.  The system also needs an alternative to
the code path which halts code execution.

      In the technique disclosed herein, an interface is provided in
the system ROM control program that allows software to set a
Halt/Reboot flag.  This flag is interrogated in the NMI code when a
catastrophic error is detected.  The default value for this flag is
"Halt."  In this case, the NMI code saves an event flag in
battery-backed memory noting the type of NMI and then halts the
system.  If a user sets the flag to "Reboot", the NMI code saves the
event flag and then resets the system.  This reset causes another
boot of the operating system.  When the system reboots, the
application can interrogate the event flag to determine the cause of
the error.  This new interface can be provided for all operating
systems that use a run-time control program within the system ROM.

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