The Virtual Machine Communication Facility
The Virtual Machine Communication Facility (VMCF) is part of the CP compo
nent of VM/SP. VMCF provides virtual machines with the ability to send data to
and receive data from any other virtual machine.
VMCF is made up of five data transfer subfunctions, seven control subfunctions, a
special external interrupt (codeX'4001 ') to asynchronously alert virtual machines
to pending messages, and an external interrupt message header to pass control
information (and data, at times) to another user.
VMCF is implemented by means of subfunctions invoked using the DIAGNOSE
instruction with a code of X'68' and a special40-byte parameter list called
VMCP ARM. A VMCF subfunction is indicated by a particular subfunction code
in the VMCPFUNC field in the parameter list.
Note: Before you can use any other VMCF subfunction, you must use theAUTHORIZE subfunction for communications. Before you can communicate with
another user, that user must also have used theAUTHORIZE sub function.
A special external interrupt (codeX'4001 ') is used by module DMKVMC to notify
one virtual machine of a pending transfer of data. This interrupt is also used to
synchronize sending and receiving of data.
Along with this interrupt, the virtual machine receives a message header that is
logged into a preassigned virtual storage area. This message header is used to
define the type of request and to provide data transfer information, such as length
of data. The message header is also used to notify the originator of a transaction
of the success or failure of the transaction. In this case, the message header
includes such information as residual counts and data transfer return codes.
Figure 6 on page 84 lists the VMCF sub functions and gives a brief description of
each. The subfunctions are described in detail in the section"Descriptions of
VMCFSubfunctions". Messages and data are directed to other virtual machines logically via the userid.
Data is transferred in up to 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 stor
age page per virtual machine (a total of two pages, one for the sender and one for
the receiver) need to be locked during the data transfer.
The special message facility uses VMCF to send messages from one virtual
machine storage area to another virtual machine storage area. For a description of
the special message facility and how it uses VMCF, see"Special Message Facility" in this section.
The Virtual Machine Communication Facility 83
The Virtual Machine Communication Facility (VMCF) is part of the CP compo
nent of VM/SP. VMCF provides virtual machines with the ability to send data to
and receive data from any other virtual machine.
VMCF is made up of five data transfer subfunctions, seven control subfunctions, a
special external interrupt (code
to pending messages, and an external interrupt message header to pass control
information (and data, at times) to another user.
VMCF is implemented by means of subfunctions invoked using the DIAGNOSE
instruction with a code of X'68' and a special
VMCP ARM. A VMCF subfunction is indicated by a particular subfunction code
in the VMCPFUNC field in the parameter list.
Note: Before you can use any other VMCF subfunction, you must use the
another user, that user must also have used the
A special external interrupt (code
one virtual machine of a pending transfer of data. This interrupt is also used to
synchronize sending and receiving of data.
Along with this interrupt, the virtual machine receives a message header that is
logged into a preassigned virtual storage area. This message header is used to
define the type of request and to provide data transfer information, such as length
of data. The message header is also used to notify the originator of a transaction
of the success or failure of the transaction. In this case, the message header
includes such information as residual counts and data transfer return codes.
Figure 6 on page 84 lists the VMCF sub functions and gives a brief description of
each. The subfunctions are described in detail in the section
VMCF
Data is transferred in up to 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.
age page per virtual machine (a total of two pages, one for the sender and one for
the receiver) need to be locked during the data transfer.
The special message facility uses VMCF to send messages from one virtual
machine storage area to another virtual machine storage area. For a description of
the special message facility and how it uses VMCF, see
The Virtual Machine Communication Facility 83