DKKVATPX ---Update the shadow table. DKKVATSX -- Invoked by DKKPRGIN when a segment exception is received for an EC
mode virtual machine. DM!{VAT, Perform setup operation, then invalidate the shadow page table or if
none exists, allocate a new shadow table and set it invalid. DMKVATPF via DMKVATPG from DKKPRG to simulate pseudo page fault
interrupts when a paging exception occurs with pseudo page fault
interrupts enabled. DKKPTRAN ' -- BrIng in the DASD page. DKKPRGSK ---aeflect program check X'14' to the user. DMKVAT, PAGRES ---When the--page becomes resident in storage. Build the PGBLOK, set high order bit in the translation exception address field, !!1!KDSP£1! Exit to dispatcher. ALLOCATION AND DEALLOCATION OF DASD SPACE Entry to search and allocate a DASD page for paging/spooling. DMKPGTSG ---Search appropriate RECBLOK chain for available D1SD page. If none
found, locate next available cylinder and construct a new RECBLOK, calculate address of the allocated DASD page and place it in Rl. Return to caller • Entry to deallocate DASD page used for paging and spooling. Via RDEVBLOK locate the RECBLOK and reset appropriate bit in the RECBLOKs RECMAP and adjust the member of DASD pages in use. If all the pages
on the DASD cylinder have been deallocated, deallocate the cylinder.
Exit to caller. Entry to release a group of DASD pages no longer needed for spool
file use. Per Rl, find RECBLOK and dumay RECBLOKs and reset the RECKAP bits as specified. Free related RECBLOKS, if co.plete
deallocation occurs. DKKPGTCG -- Entry for allocation of enough DASD spool space to record a 3704/3705 du.p. Scan RDEVBLOK and associated ALOCBLOK for enough contiguous
available space to record the du.p. When found, flag cylinder as
allocated and build and chain the required RECBLOKs. Dl!KPGTVG ---niiPGT contains an internal table, PAGETABL, in which the allocation
of page frames for the CP paging VKBLOK is kept. The PIGETABL is
scanned for a zero bit denoting the page fra.e is available. The
page is marked allocated by setting the bit to one and the address of
the page fra.e is returned to the caller in Rl. If no page fra.es
are available, a CPEXBLOK is built and queued to the deferred request
chain. DKKPGTVG to release a page of virtual storage. Check the chain of
deferred requests. If there are none, reset the page bit in the PAGETBL to 0 and exit to the caller. Otherwise, give the page to the
first requestor in the deferred chain and stack his CPEXBLOK for the
dispatcher. CP Method of Operation and progra. Organization 1-205

SHARED SEGMENT STORAGE MANAGEMENT Entry via SVC from STORE command is to
the CP command will
a private copy. DPIKERMSG the command processor if an ADSTOP, TRACE, or
alter a shared page. The virtual machine issuing
be unshared from the named system, that is, given ---rhe-running virtual machine is informed of the share page violation. Entered from DMPDSP or DMKPTR via BALR. The protected shared page
tables are examined for hardware change bit being on. The resulting
condition code is reflected to the caller. Entered to switch the virtual machine from one set of page tables to
the other. TEPIPORARY DISK STORAGE MANAGEMENT DMKTDKGT to allocate temporary disk space (T-disk). With RO equal to
the number of cylinders required and R1 equal to the device type,
locate RDEVBLOK and related ALOCBLOK's ALOCMIP. If no allocation
space is to be found, return to caller with 0 in RB. If allocation
is successful, flag ILOCMIP, with X'AA' as allocated and put first
cylinder address in R1 and RDEVBLOK pointer in RS and return to
caller. PAGING I/O SCHEDULER DMKPAGIO -- Entry to initiate Page I/O activity. Using preformatted IOBLOK from lOBSTICK, fill in the CCWs with DASD opcode and values derived from CPEXBLOK swap table and core table. Chain the CPEXBLOK on the
in-transit queue. Q!KPA§, Find the Paging RDEVBLOK. FI!Q!Q!! Search IOBLOKs seeking the same cylinder address. If found, chain
the channel programs together with TICs. DMKDSPCH the dispatcher. If no IOBLOKs with some cylinder address are found - Start the I/O operation. DMKDSPCH ----EiIt-to the dispatcher to await interrupt. Upon interrupt return, unchain the CPEXBLOK from the intransit queue. DMKSTPCP ---Stack all deferred requests for execution. Return IOBLOK to lOBSTICK or free it. Calculate paging load and store it, the TOD, and other values in PSI. DMKDSPCH ---ExIt-to dispatcher. 1-206 IBPI VPI/370 System Logic and Problem Determination--Volume 1