System for directly and indirectly accessing control registers b

Details System for directly and indirectly accessing control registers b System for directly and indirectly accessing control registers b

1987-01-21

1989-05-30

Williams, Jr., Archie E.

Boots, shoes, and leggings

G06F 1338, G06F 922, G06F 944, G06F 946

Patent

active

048356778

ABSTRACT:
A data processing system comprising at least two operating systems (OS1, OS2) for virtual machines, a supervisory operating system, i.e., a control program (CP) for controlling the operating systems, control registers (CR0, CR1, ---) and an extended control register (ECR) having a special bit. When a control register operating instruction (LCTL or STCTL) is executed by one of the operating systems, the special bit has a first value and the operating system directly accesses the control register. When the other of the operating systems attempts to execute such a control register operating instruction, the special bit has a second value and an interruption is generated in the supervisory operating system.

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