DMKGRF DMKLOG DMKMID DMKMSG DMKMSW DMKNES DMKNLD DMKPAG DMKPTR DMKQCN DMKRGA DMKRGB DMKRNH DMKSPL DMKVCA DMKVCH DMKVDA DMKVDD DMKVMC Figure 23.
Action
Locks the virtual machine that was last dispatched.
Locks the virtual machine just built.
Locks the virtual machine being set as favored. LOCKS the virtual machine associated with a real device
block.
Locks the virtual machine whose virtual device is being
reset when a real device is halted.
Locks each virtual machine in order to prepare the VMBLOK for uniprocessor mode. Locks the virtual machine whose storage is being locked or
unlocked, or for whom accounting is being done.
Locks the virtual machine receiving transferred spool
files.
Locks the virtual machine of the dialed system, the virtual machine of the line being dropped (DMKDIADR;, or the
virtual machine that owns the channel-to-channel adapter
being coupled.
Locks the virtual machine associated with a real device
block.
Locks the virtual machine being reconnected or the virtual
machine being autologged.
Locks the virtual machines receiving messages at midnight. Locks the virtual machine receiving a message. Locks the system operator.
Locks each virtual machine active when the NETWORK SHUTDOWN command is processed.
Locks the virtual machine associated with a real device
block.
Locks the virtual machine associated with a queued I/O request.
Locks the virtual machine from which a page will be stolen.
Locks the system operator.
Locks the virtual machine associated with a NICBLOK. Locks the virtual machine associated with a CONTASK or a
NICBLOK.
Locks the virtual machine of the destination user for a
console task or the virtual machine associated with a remote teleprocessing line.
Locks the virtual machine receiving a transferred spool
file or the virtual machine owning a spooled reader file" Locks the virtual machine of the coupled-to CTCA.
Locks the virtual machine to which the channel is being
attached, or the the virtual machine from which the
channel is being detached.
Locks the virtual machine involved in attaching or
detaching a real device.
Locks the virtual machine involved in detaching a real
device.
Locks the virtual machine to which the caller is communica ting.
odules that Obtain Additional VMBLOK Lock
CP Introduction 1-175

obtained, normal DMKMCH processing continues. If the lock cannot be
obtained, DMKftCH stacks a CPEXBLOK with CPftCBLK set and exits to DMKDSPRU. This CPEXBLOK causes processing to resume at DMKftCHSE with the
global system lock held. Any machine checks that occur before the CPEXBLOK processing has completed are considered recursive machine checks and handled appropriately. If the control program was in control
and the system is not to be terminated, the machine check handler saves
status in the CPEXBLOK, set CPMCHLK and reloads MCOPSW. CPftCHLK is set
to prevent the dispatcher from starting any new work on this processor
until the machine check processing has completed. DMKMCH passes control to DMKftCTPT if the system is running in
attached processor mode and a decision has been made to terminate the system. In general, if a virtual machine was running when the machine chsck occurred, only that virtual machine is terminated. DMKMCTPT determines if the system can continue and if the processor
can continue. For the attached processor, if the machine check was not
a clock error and the control program was not in control, the virtual machine running at the time of the error is terminated. If the machine check was a clock error on the main processor or the control program was in control on either processor, the other processor is signalled to stop
and store status and a wait state PSW is loaded on the failing
processor. An attempt is made to issue message 610W to the operator
before the main processor is stopped. If the machine check was a clock
error on the attached processor and the control program was not in
control, the main processor is signalled via an external call to
initiate automatic processor recovery with an indicator to continue
processing.
The malfunction alert interrupt handler (DftK!CTftA) receives control from the external second level interrupt handler. If the malfunction
alert came from the main processor, a 001 wait state PSW is loaded. If
the malfunction alert came from the attached processorand a virtual machine was in control, an indication is set to terminate the virtual
user and CPAPBPND is set for processor recovery. If the attached
processor was in supervisor state, message 610W is sent to the operator
and a 013 wait state PSi is loaded. If the attached processor was in a wait state, CPAPRPND is set for processor recovery.
The automatic processor recovery routine (DftKMCTPB) receives control
from the external SLIH or the dispatcher. If the system is to continue
processing, the vary processor offline routne (DftKCPUUP) is called. DMKCPUUP examines the chain of virtual machines for attached processor
affinity and shared segment pointers. Any shared segment pointers for
the attached processor are switched to point to the main processor
shared segments. All the system control blocks and save areas necessary
to run in attached processor mode are also freed. The time froa the
first timer request queue element is placed into the clock comparator
for the main processor. While preserving the maintained fields in the absolute zero area, the main processor's prefix storage area is copied to the absolute zero area
and prefixing is stopped. The attached processor operational flag is turned off in the absolute zero area, and the prefix storage areas for
the main and attached processors are freed. The pages and DISD slots
held by the attached processor for shared segments are freed by D!KPGT and DMKPTR. A message (194I) is issued, and return is made to DftK!CTPR. For any virtual machines with affinity to the attached processor, DMKMCTPR resets the affinity for each, issues message 6211, and puts the
machine in console function mode (if the virtual machine is not
disconnected). If a virtual machine is to be terminated, the virtual machine is reset, messages 616I and 6191 Normal return canses the system to continue processing in uniprocessor mode. 1-176 IBM VM/370 System Logic and Problem Determination--Volume 1