SET
When affinity is in effect for a virtual machine, only the speGified processor runs the virtual machine. This is
particularly useful for virtual maGhines that require features or performance enhancements that are only available on one processor in an attached processor system. CP instructions (sach as privileged operation instructions) executed on behalf
of a virtual machine are not restricted to a processor by an
affinity settinq. CPUID bbbbbb COUID is the keyword that provides a means of setting or
changinq the CPU identification for a virtual machine. The
variable value bbbbbb represents a string of six hexadecimal
digits that permit unique identification of the :PU. This command allows the user to provide a unique CPU identification
to be stored in response to the 'STIDP' instruction. It is
necessary to associate a unique CPUID with each virtual
machine that is attached to an port since
solicited/unsolicited messages are directed to the host system by means of the CPUID. There is no checking by VM/370 to
ensure that all virtual machine using the SET CPUID command
have specified unique CPU serials. The hexadecimal field
'bbbbbb' is the CPU identification number (CPU serial).
The COU identification number (serial) is only a portion of
the complete CPUID. The CPUID identification stored in
response to a STIDP instruction is a string of 16 hexadecimal
digits as follows:
aabbbbbbccccdddd
aa version code; these two digits are forced to X'FF' to identify that the virtual machine is running
under VM/370. bDbbbb - CPU identification number; this field contains six
hexadecimal digits. This is the only part of the COUlD that can be set by the DIRE:TORY OPTION control statement and modified by means of the SET CPUID command.
model number; this field contains a
digit followed by the three digits
number (0-9). This field defaults
number of the real machine.
high order 0 of the model
to the model
dada machine check extended logout; this field is forced
to x'OOOO' since CP does not reflect machine checks
back to the virtual machine. Section 5. Format of CP Commands 133

SET ASSI ST r , r , r , JON , , I I T M R I , I INOSVCI L J L J L .J OFF All functions of SET ASSIST operands pertain to VK/370 hardware assist. VM/370 hardware assist consists of processor
hardware that assists the processor in the execution of
certain instructions, series of instructions, privileged
operations, and interrupt that are normally handled by the control program portion of VM/370. In attached systems, VM/370 hardware assist is available for
installation on either or both processors.
All, some, or none of the function performed by VK/370 hardware assist may be available on the processor or attached
processor that the virtual machine is logged on. (For the
extent of hardware assist available on supported VK/370 processors, refer to the QYigg.) The extent
of VM/370 hardware assist available to your virtual machine
can be determined by invoking QUERY SET and by the responses
to attempts to invoke the various operands of SET ASSIST. The
hardware assist functions can only be activated for an
individual virtual machine provided the VM/370 system operator
permits the associated hardware assist function to be active
for the entire system (or in attached processor systems, the
appropriate processor). Overall system control of hardware
assist is controlled by SET SASSIST and SET CPASSIST commands;
see the Guigg for details on these commands.
If VM/370 hardware assist is active for the entire system,
then hardware assist is active and used during virtual machine
operations immediately after logon. Hardware assist as it
pertains to a virtual machine can then be turned off and on
aqain by SET ASSIST OFF and SET ASSIST ON respectively.
The SVC handling portion of the hardware assist is invoked
when you log on unless your VK/370 directory entry has the SVCOFF option. Issue the QUERY SET command line to see if the
hardware assist is activated and whether the hardware assist
or VM/370 is handling SVC interruptions. All SVC 76 requests
are passed to CP for handling, regardless of the SVC and NOSVC operands. If you issue the SET ASSIST command line and
specify SVC or NOSVC while t he hardware assist is turned off,
the appropriate bits are set. Later, if hardware assist is
turned on again, the operand you specified while it was off
becomes effective. ON sets the hardware assist on for the
virtual machine; OFF turns it off. SVC specifies that the
hardware assist handles all SVC interruptions except SVC 76 for the virtual maChine; NOSVC means VK/37D handles all the SVC interruptions.
If the user requests VMi370 hardware assist and it is
available and active, the request is honored; if VK/370 hardware assist is not active but is available and the user
attempts to enable hardware assist, the virtual machine
remembers the enabling attempt and an appropriate message is
sent to the Qser. When the system operator enables hardware
assist, it is immediately utilized by the virtual machine. In
the that hardware assist is not available or active on
the system, an appropriate error message is issued. In an
attached processor system, hardware assist is available to any
virtual machine provided it is installed on one of the 134 IBM VM/370 CP Command Feference for General Users