!1arch 3, 1980 48.4 IBM VM/370 Planning and System Generation Guide

Planning Considerations for Other Virtual Kachines Kessages and data directed to other virtual machines are logically
identified via the virtual machine's userid. Data is transferred in
2048-byte blocks from the sending virtual machine's storage to the
receiving virtual machine's storage. The amount of data that can be
moved in a single transfer is limited only by the sizes of virtual
machine storage of the respective virtual machines. Use of real storage is minimal. Only one real storage page need be
locked during the data transfer. A special interrupt is used to notify
one virtual machine of a pending transfer of data; this interrupt is
also used to sending and receiving of data. Under the Special Kessage Facility, CP acts as a virtual machine in
behalf of a virtual machine that issues the CP command SKSG. The
receiving virtual machine, properly programmed to accept and process
special messages, authorizes itself to CP. Data (message) transfer is
from CP, via the message and VKCF modules. SUMMARY OF VKCF FUNCTIONS VMCF functions include five data transfer operations and seven control
functions. Figure 8 contains a brief summary of VKCF functions. A more
detailed description of these functions and how they are implemented in VK/370 is contained in the programmer's The data transfer operations involve the movement of data from one
virtual machine's storage to another virtual machine's storage. The VMCF control functions allow a user to manage data transfer operations
from the virtual machine console. VKeF is implemented via the CP not hardware dependent. VKCF is VK/370 virtual machine. DIAGNOSE instruction in VM/370; it is
available to any logged-on, authorized Part 1. Planning for System Genera tion 49