Browse Prior Art Database

Automatic Logon of Virtual Machines During System Startup or Restart

IP.com Disclosure Number: IPCOM000081554D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Helfer, MS: AUTHOR

Abstract

The technique described herein permits a designated virtual machine to automatically logon a virtual machine system such as IBM VH/370. The automatic logon occurs during system startup, i.e, either a cold startup or a system restart resulting from a system failure. The logon takes place without operator intervention or assistance.

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Automatic Logon of Virtual Machines During System Startup or Restart

The technique described herein permits a designated virtual machine to automatically logon a virtual machine system such as IBM VH/370. The automatic logon occurs during system startup, i.e, either a cold startup or a system restart resulting from a system failure. The logon takes place without operator intervention or assistance.

The logon of the designated virtual machine is carried out during the initialization period of system startup. During this period, the system (such as VM/370, for example) is completely resident in real main memory but the CPU is under the control of the initialization program. Having the system completely in real main memory during initialization implies that, during the latter phases of system initialization, all system functions are available to the initialization program. Such arrangement is important to the implementation of the automatic virtual machine startup.

The automatic startup procedure consists in the calling of the standard system modules that are used for logging a user into the system. In this connection, the initialization program of a system such as the VH/370 and the system modules which are employed at logon, are modified to recognize a logon from the initialization program and not to utilize the normal return paths. This signifies that, at the end of system initialization, the new virtual machine has been logged onto the system, in the sense that all of its control blocks have been established. However, it has not yet started to run, i.e., execute. In fact, at this point the system is not yet operational. In this connection, immediately prior to turning control over to the system, the dispatcher and scheduler therein have to be informed that there is a virtual machine on the system which is executable. Such informing is accomplished by, in effect, creating a condition which causes the dispatcher/scheduler to consider the logged on virtual machine, as one which has been executing in the past and is a candidate for redispatching.

The virtual machine which is automatically logged onto the system at startup has to have an IPL of a device or system specified in its directory. This is necessary t...