Browse Prior Art Database

Method to Convert Checkstops on a Graphics I/O Bus to Interrupts on the System I/O Bus

IP.com Disclosure Number: IPCOM000113183D
Original Publication Date: 1994-Jul-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Arimilli, LB: AUTHOR [+3]

Abstract

Disclosed is a method to convert checkstops generated by adapters on a Graphics I/O Bus to less severe interrupts that are presented to the processor via the processor's System I/O (SIO) Bus.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 94% of the total text.

Method to Convert Checkstops on a Graphics I/O Bus to Interrupts
on the System I/O Bus

      Disclosed is a method to convert checkstops generated by
adapters on a Graphics I/O Bus to less severe interrupts that are
presented to the processor via the processor's System I/O (SIO) Bus.

      The processor should not be checkstopped every time an adapter
on the Graphics I/O bus detects a checkstop condition, because an
error such as a bus parity error may be recoverable if the operation
is re-tried by software.  Software can checkstop the processor if the
parity error is a hard error and not recoverable.  Otherwise,
software can retry the operation if the error is a soft error.

      An External Interrupt Vector Register and an Error Log Register
are added to the I/O controller which provides the interface between
the System I/O Bus and the Graphics I/O Bus.  The External Interrupt
Vector Register is initialized by software during the IPL sequence.
When an adapter drives its checkstop line to the I/O controller, the
I/O controller sets the corresponding adapter's checkstop bit in the
Error Log Register and generates an External Interrupt to the
processor (via the SIO bus) using the interrupt vector in the
External Interrupt Vector Register.

      This method allows a checkstop by an adapter on the Graphics
I/O bus to be reported as an External Interrupt on the SIO bus to the
processor, thereby allowing software the opportunity to retry the
operation and a...