available system CORTABLE for the
pointers to make in this CORTABLE
page in a system
resource. This is accoaplished by locating the
defective page and altering the CORFPNT and CORPBPIT the page unavailable to the systea. The CORDISl bit
is set on to identify the reason for the status of this
d Ullp. The recovery facility mode switching subroutine (DftKftCHftS) allows the
service representative to change the mode that processor retry and ECC
recording are operating This subroutine receives control when a
user with privilege class F issues some fora of the SET co •• and with the MODE operand. A check is initially made to determine if this is V!/370 running under VM/370. If this is the case, the request is ignored and
control is returned to the calling routine. For the format and usage of
the SET command with the ftODE operand, refer to the !M/370 Q2erator's The operator communciation subroutine is invoked when the integrity of
the system has degraded to a point where autoaatic shutdown and reload
of the system has been tried and was unsuccessful, or could not be
attempted due to the severity of the hardware failure. 1 check is first made to determine if the system operator is logged on as a user, next a
check is made to determine if the syste. operator is disconnected. If
either of these checks is not affirmative a aessage cannot be issued
directly to the systea operator. A LPSW is performed to place the
processor in a disabled wait state with a recognizable wait state code
in the processor instruction counter.
The virtual machine termination subroutine selectively resets or terminates a virtual user whose operation has been interrupted by an
uncorrectable machine check. First, the aachine is marked nondispatchable to prevent the damaged machine from running before reset
or termination is performed. The machine check record is formatted and DftKIOEftC is called to record the error. Then the user is notified by a
call to DftKQCNWT that a machine check has occurred and that his
operation is terminated. The primary system operator is notified of the
virtual user termination by a message issued by a call to D!KQCIWT. If
the virtual .achine is running in the virtual=real area, D!KUSO is
called to log the virtual machine off the systea and to return the
storage previously allocated to the virtual .achine and to clear any
outstanding virtual machine I/O requests. The HOLD option of LOGOFF is
invoked to allow a user on a dial facility to retain the connection and
thus permit LOGON without re-establishing the line connection. However,
if the virtual machine is running in the virtual area, and D!KCF! is
then called to put the virtual machine in console function .ode, the
user must re-initialize the system to co.mence operation. CP Introduction 1-155

The soft recording subroutine performs two basic functions: • Formats a machine check record and calls D!KIOE!C to record the error
on the error recording cylinder. • Maintains the threshold for processor retry and ECC errors and
switches from recording to quiet mode when the threshold value is
exceeded. To accomplish this, a counter is maintained by D!K!CH for
successful processor retry and corrected Bee Recording mode (bit 4 of control
register 14 set to one) is the initialized state, and normal operating
state of VK/370 for processor retry errors. Recording mode may also be
entered by use of the CP SET command. When 12 soft machine checks have
occurred, the soft recording subroutine switches the processor from recording mode to quiet mode. For the purpose of model-independent implementation this is accomplished by setting bit 4 of control register
14 to zero.. Because in quiet mode no soft machine check interruptions
occur, a switch froa quiet mode to recording mode can be made by issuing
the SET MODE RETRYIKAIN RECORD command. While in recording mode, corrected CPU RETRYIKAIN reports are formatted and recorded on the V8/370 error recording cylinder, but the primary systems operator is not informed of these occurrences. Quig! Quiet mode (bit 4 of control register 14 set
to 0) can be entered in one of two ways: (1) when 12 soft machine checks have occurred, or (2) when the SET !ODE RETRY QUIET command is
executed by a class F user. In this mode, both processor retry and ECC
reporting are disabled. The processor remains in quiet mode until the
next system IPL (warm start or cold start) occurs or a SET !ODE RETRYI!AIN RECORD command is executed by a class F user. SET KODE 81IN is treated as invalid on a 3031, 3032, or 3033 processor.
ECC To achieve model-independent support, RKS does not
set a specific mode for ECC recording. The mode in which ECC recording
is initialized depends upon the hardware design for each specific
processor model. For the IBM System/370 Models 135, 135-3, 138, 145,
145-3, 148, 158, 168, 3031, 3032, and 3033, the hardware-initialized
state (therefore the normal operational state for V!/370) is quiet mode. For the IB! System/370 Models 155 II and 165 II, the hardware
initialized state (the normal operational state for V!/370) is record mode. An automatic restart incident due to a V8/370 failure does not
reset the ECC recording mode in effect at the time of failure.
The change from record to quiet mode for ECC recording can be
initiated in either of the following ways: (1) by issuing the SET KODE {MAINIRETRY} QUIET co.mand, or (2) automatically whenever 12 soft machine checks have occurred. For the purpose of model-independent
implementation, this occurs by setting bit 4 of control register 14 to
zero.
The change from quiet to record mode for ECC recording can be
accomplished by use of the SET KODE KAIN RECORD com.and. This recording mode option is for use by maintenance personnel only. It should be
noted that processor retry is placed in recording mode if it is not in
that state when the SET MODE !AIN RECORD command is issued. While in recording mode, corrected Eee reports are formatted and
recorded on the error recording cylinder, but the primary systems operator is not informed of these incidents.
1-156 IBM VM/370 System Logic and Problem Determination--Volume 1