related and that must all be turned off to disable the function, see the
following instruction cross-reference list.
Those hardware-assisted functions that are not in
turned off individually without being concerned about
that may call it.
the list may be
other functions
The SVC8 and SVC12 functions of CP assist can be disabled by certain input parameters in the VMALIST to extreme values. The var10US functions provided by expanded virtual machine assist are controlled by
the setting of bits in the MICBLOK's assist control field, see the topic "Expanded Virtual Machine Assist" for details.
Function DECCW'1-- DSP2 FRET PTRLK PTRUL RETURN SHARED TRANBRNG ZAPPAGE ZAPSEGS Invoke,g !!I DECCllO DSP1 UNTFR, DSP2 CCllGENRL, TRANLOCK UNTFR CCllGENRL, UNTFR DSP2 DECCll1 ZAPSEGS DSP2, PTLB lote: Be careful when making these functions NOOPs. For exaaple, to
completely turn off ZAPPAGE, ZAPPAGE and ZAPSEGS must be made NOOPs. But ZAPSEGS is invoked by DSP2 and PTLB. Therefore, DSP2 and PTLB must both be made NOOPs. DSP2 is invoked by DSP1; therefore, DSP1 must also
be made a NOOP. The end result must be that DSP1, DSP2, PTLB, ZAPZEGS and ZAPPAGE must all be turned off. Bote: DSPO, DSPl and DSP2 CP ASSIST instructions are changed to NO-OP instructions in PrQdu£!, program No. S748-IE1.
As an example, assume that you want to defeat the FRET hardware-assisted
function. 1.. Look up FRET in the
FRET is invoked by
Therefore, the four UNTFR, DSP2, and DSP1. Instruction/Function Cross Reference List. UNTFR and DSP2. DSP2 is invoked by DSP1. functions that must be deleted are: FRET,
2. FRET is part of DMKFRE, UNTFR is part of DMKUNT, DSP2 and DSP1 are part of DMKDSP. These are the modules that contain the
hardware assisted code that must be made NOOPs. 3. Listed in the CPATABLE points:
list of DMKCPI are the following entry
DMKFRET which contains the CP assist instruction EG01 DMKUNTFR which contains the CP assist instruction EGOS D!KDSP1 which contains the CP assist instruction EG07 DMKDSP2 which contains the CP assist instruction E611
Appendix A: VM/370 Extended Control-Program Support 1-419

4. The load aap for your V!/370 system entry points, and their locations.
lists the modules and
5. Using the DKKCPI list to find the CP assist op code and entry
point name, and the load list to find the location of that
entry point, replace the CP assist instructions (X'E6xxxxxxxxxx') in those locations with three NOOPs (1'470000000700'). All CP assist instructions cause operation exceptions if ECPS is not The CP assist instructions are executed as NOOPs if the PSi is in supervisor state and VM/370 ECPS is installed but the CP assist is
disabled in control register 6. If VM/370 ECPS is installed but the PSi is in a problem state, the CP assist instructions cause privileged
operation exceptions regardless of the setting of control register 6 bit
6. EXPANDED VIRTUAL !ACHINE ASSIST Expanded virtual machine assist is part of the V!/370 Extended
Control-Program Support. Expanded virtual machine assist is hardware
that executes certain privileged operations issued by a V!/370 virtual
aachine. Expanded virtual machine assist is an extension of the Virtual !achine Assist feature. Expanded virtual aachine assist is invoked only
if virtual machine assist cannot execute the subject instruction in the
virtual machine, a corresponding virtual aachine assist function is
defined, and that virtual aachine assist function would present a
privileged operation exception. In soae cases, expanded virtual machine
assist does not completely execute the subject instruction.
The following table sum.arizes the operation codes, instruction naaes, amount of execution of the instruction by expanded virtual aachine
assist, and descriptions of the instructions:
Amount of
Trace Execution
Table of VK/370 Virtual Machine 2R 11l!!:I In§!!:Y£!!.Q!l rY!lf!!.Q!! 82 Yes LPSi Partial Load PSi B20D No PTLB Complete Purge Table Lookaside Buffer B206 Yes SCKC Partial Set Clock Comparator
9C Yes SIO,SIOF Partial Start I/O, Start I/O Fast B208 Yes 5PT Partial Set CPU Timer 80 Yes 5S! Partial Set System "ask AC Yes 5TNS! Partial Store Then AND System "ask AD Yes STOSM Partial Store Then OR System Mask B209 No STPT COllplete Store CPU Tiller 9F No TCH Complete Test Channel 1-420 IBM VM/370 System Logic and Problem Deterlination--Volume 1