This paper describes the evolution of facilities for virtual machines on IBM System/370 computers, and presents the elements of a new architectural facility designed for the virtual-machine environment. Assists that have been added to various System/370 models to support the use of virtual machines are summarized, and a general facility for this purpose which was introduced with the System/370 Extended Architecture (370-XA) is described. A new instruction of the 370-XA architecture places the machine in a specific mode in which several special capabilities are enabled. These allow the machine to provide execution in the virtual-machine environment of most of the instructions (including many privileged instructions) and most of the facilities (such as dynamic address translation) of both the System/370 and the 370-XA architectures. The major features of this new facility are individually discussed and summarized.
[1]
Andris Padegs.
System/360 and Bayond
,
1981,
IBM J. Res. Dev..
[2]
R. L. Cormier,et al.
System/370 Extended Architecture: The Channel Subsystem
,
1983,
IBM J. Res. Dev..
[3]
Andris Padegs.
System/370 Extended Architecture: Design Considerations
,
1983,
IBM J. Res. Dev..
[4]
Robert J. Creasy,et al.
The Origin of the VM/370 Time-Sharing System
,
1981,
IBM J. Res. Dev..
[5]
Richard A. MacKinnon.
The Changing Virtual Machine Environment: Interfaces to Real Hardware, Virtual Hardware, and Other Virtual Machines
,
1979,
IBM Syst. J..