Browse Prior Art Database

Logical IPL Selection Mechanism

IP.com Disclosure Number: IPCOM000061174D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 64K

Publishing Venue

IBM

Related People

Chisholm, DR: AUTHOR

Abstract

This article describes an initial program load (IPL) mechanism wherein the IPL identifier identifies the IPL record to be loaded rather than where the record resides. Provision is made for multiple and various IPL selections in an advantageous manner which further involves diagnostics and automatic retry if IPL fails. One IPL mechanism in general use is a physical selection mechanism. A physical and logical IPL selection mechanism is disclosed herein which is comprised of two basic parts as follows: - An architected IPL Identifier. - A microcode-controlled initiation sequence with an architectural processor bus operation (PBO)). The IPL identifier (ID) should be architected as an eight-bit field that can be altered from the system console and read by the microcode controlling the initiation of IPL.

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Logical IPL Selection Mechanism

This article describes an initial program load (IPL) mechanism wherein the IPL identifier identifies the IPL record to be loaded rather than where the record resides. Provision is made for multiple and various IPL selections in an advantageous manner which further involves diagnostics and automatic retry if IPL fails. One IPL mechanism in general use is a physical selection mechanism. A physical and logical IPL selection mechanism is disclosed herein which is comprised of two basic parts as follows: - An architected IPL Identifier. - A microcode-controlled initiation sequence with an architectural processor bus operation (PBO)). The IPL identifier (ID) should be architected as an eight-bit field that can be altered from the system console and read by the microcode controlling the initiation of IPL. One bit (probably the most significant) should be architected as the physical/logical (P/L) selection bit. The P/L bit qualifies the remainder of the ID as either a physical selection ID or a logical selection ID. The following depicts a possible IPL ID format:

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Physical selection settings have a one-to-one correspondence with a physical attribute (hardware jumpers or switches) of the IPL I/O processor. Logical selection settings identify the type of IPL record rather than where the IPL record resides. The logical selection settings have a one-to-one correspondence with an IPL label on the media itself. The labels should be architected to identify the type of bootstrap or system that is to be loaded rather than media or device characteristics. The second part of the IPL mechanism is the microcode- controlled initiation sequence. The microcode must have the capability of reading the IPL ID when either the Load button is depressed or a power-on sequence occurs with "Auto Load" indicated. The IPL microcode constructs and issues architected broadcast write type PBOs to IOPs (input/output processors). The microcode...