ConditiOil Codes: When DIAGNOSE Code X'74' processing completes, one of the
following condition codes is placed into register Ry and returned to CP:
Return Code X'OO' X'04' X'OS' X'OC' X'lO' X'14'
X'lS'
X'lC'
Meaning
Load/ save successfully performed
Named system not found
Named system currently active
Volid for system not CP owned
Volid for system not mounted
Too many bytes to load/save; residual byte count is in Ry+ 1
Paging error during load/save
Too few bytes to LOAD/SAVE. Needed byte count is in Ry+ 1.
DIAGNOSE Code X'78' -- MSS Comnlunication
Privilege class G DIAGNOSE Code X'7S' is used to communicate with the VM/SP control program
about MSS volume mounts and demounts.
Entry Values: The Ry register contains a subfunction code. The valid subfunction
codes and their meanings are: X'OO' - The virtual machine issuing the DIAGNOSE instruction is running OS/VS with MSS support and the DMKMSS program for MSS
communication. The Rx register contains the device address of the virtual
machine's MSS communicator virtual device. X'04' - The virtual machine is ready to process an MSS request. The MSSCOM block representing the request should be placed at the virtual
machine address indicated by the Rx register. X'OS' - An MSS request represented by the MSSCOM block located at the vir­
tual machine address indicated by the Rx register has been accepted by the
MSC. • X'OC' - An MSS request represented by the MSSCOM block located at the vir­
tual machine address indicated by the Rx register has been rejected by the
MSC.
X' 10' - The DMKMSS program is no longer available to process MSS requests.
X'14' -The DMKMSS program has created a list of all VUAs associated with
this processor (cpuid) and requests CP to build its shared and non-shared SDG
tables from that list.
Error Conditions: If the DIAGNOSE Code X'7S' is specified incorrectly, CP ter­
minates the user program with one of the following exceptions: DIAGNOSE Instruction in a Virtual Machine 259

Error Return (DMKHVC)
Protection Exception No DMKSSS module exists
Specification Exception MSSCOM crosses a page boundary DIAGNOSE Code X'78' condition codes and return codes are: CONDITION CODE=O Successful completion. CONDITION CODE= 1 (DMKSSS) Error Condition. Register 15 contains one of
the 'following: RC=12
RC=16
Subfunction code was either less than zero or
greater than 16.
Subfunction code was within the valid range,
but not a multiple of 4.
Addressing exception trying to bring in the
buffer page.
Issuer is not the issuer of subfunction zero. DIAGNOSE Code X'7C' --Logical Device Support Facility I Privilege class G DIAGNOSE Code X'7C' allows an application running in a virtual machine to
drive a logical 3270 as if it were a real display station locally attached to the
VM/SP system. Communication between the application and the logical device is
done via the DIAGNOSE interface and a new external interrupt code.
Entry Values: Rx is a user-specified register (not GR15) containing the logical
device number that is used to coordinate CP and local system operations. It is not
used for the INITIATE function.
Rx+ 1, for the INITIATE function, this register contains in the low-order three
bytes the device model, class, and type for the logical device to be created. For
example, a 3277 Model 2 is represented as X'00024004'. Valid device types are:
3277 Model 2, and 3278 Models 2, 3, 4, and 5.
For the ACCEPT function, this is a register that contains the address of a data
buffer.
For the PRESENT function, this is a register that contains either an address or a
complemented address. If an address, it is the address of a single buffer of data 4096 bytes or less in length. If a complemented address, it is the address of a list
that describes a data stream occupying multiple data buffers and/or greater than 4096 bytes in length.
Ry is a user-specified register (not GR15) containing the code of the logical device
subfunction to be executed:
260 VM/SP System Programmer's Guide