Last Updated: 10 March 2026

Service and feature packs released for the z/VM 7.4 CP component


z/VM 7.4 introduced linear service to the product. Service fix packs and feature packs are now released on a regular cadence. By installing the latest pack you will receive all service fixes and features for the component. Refer to the change log table below for a comprehensive list of changes to the component since the z/VM 7.4 General Availability date.

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A list of service for z/VM 7.4 CP
Release Level Available Type Crit PE Security HIPER APAR PTF Details
7.4 0307 20260310March 10, 2026 Fix pack No No No VM66925 UM90594 z/VM 7.4 CP Fix Pack - Feature 03 Fix 07
  • OSH device stuck attached to SYSTEM after VSWITCH SWITCHOVERfails
    A problem was found in a function that connects the structures for a VSWITCH uplink OSH device and corrected. A similar problem was corrected in the OSD path to avoid potential issues there.
7.4 0306 20260304March 4, 2026 Hot fix No Yes No VM66921 UM90591 z/VM 7.4 CP Hot Fix - Feature 03 Fix 06
7.4 0305 20260227February 27, 2026 Fix pack No No No VM66920 UM90590 z/VM 7.4 CP Fix Pack - Feature 03 Fix 05
Firmware D61C Bundle 20 is required
  • OSH SET VSWITCH SWITCHOVER loses connectivity when there are 2 backup RDEVs
    In this scenario, the wrong control block was being stored into our routing entry so traffic was being routed to the wrong device. Code has been updated to select the appropriate control block for the routing table after the SWITCHOVER completes.
     
  • The EQID of an EQDIO device is reset after a config off/on
    During config off processing, the deletion of the VDEV block associated with the device hung. This led to a new RDEV block being created when the device was configured back online. The new RDEV block did not have the EQID associated with it. Code has been changed to properly delete the VDEV block on config off such that the original RDEV (and EQID) are reused when the device is configured back online.
     
  • VSWITCH error recovery message indicates a "persistent error condition" which results in a recovery loop
    Code has been changed to skip enabling the recovery timer for devices that have encountered a persistent error condition.
     
  • Additional monitor counters are needed for QDIO/EQDIO
    A new monitor record (MRIODQEQ - D6 R55) has been defined to collect EQDIO queue based data. The user based counters already in MRUSEACT are also appropriately populated with this fix.
     
  • z/OS guest receives error code 03 when deactivating EQDIO virtual NICs
    Error code 03 was indicating that EQDIO simulation was processing an unexpected adapter command. This occurred because the code for cleaning up mulitcast addresses associated with the virtual NIC was assuming it was operating in layer 3 mode. Code has been updated to validate the transport mode the virtual adapter is operating in when cleaning up multicast addresses, and respond appropriately.
     
  • Eliminate unnecessary EQDIO instructions to improve efficiency
    The manner in which z/VM tracks queue indicies for EQDIO adapters has been changed to eliminate the vast majority of the queries that are issued to the adapter for ensuring indicies stay in sync. This greatly improves the efficiency with which the EQDIO support operates.
     
  • Unexpected ISOLATE message when a switch port is enabled for LAG
    Code updated to not send an ISOLATE command to the EQDIO adapter when neither ISOLATE nor VEPA is enabled.
     
  • LAG EQDIO VSWITCH does not attempt to initialize other devices if first device is disabled
    EQDIO initialzation logic has been updated to react appropriately when it encounters a device offline. Port group initialization will no longer halt when the first device is offline.
     
  • EQDIO VSWITCH loses connectivity for some guests after a hardware switch reboot
    Problem addressed through firmware and z/VM updates. For z/VM, initialization of link aggregation groups is now done in multiple steps. This is because gratuitious ARP packets that are used to announce MAC address changes when takeover events occur may be lost if they are sent before a link is fully LACP enabled. z/VM will now initially enable the EQDIO data plane for a LAG port just enough to flow LACP PDUs (but not guest data). Once the port becomes LACP enabled, the data plane will then be enabled for guest data as well and initialization will complete with full connectivity. Firmware D61C Bundle 20 is required.
     
  • ABENDHTT001 HCPIVC+16E8 with 16 members in an IVL domain
    Abend occurs when the IVL control block is allocated near the end of a 4K page. When sending a broadcast packet, the control loop stepping through the IVL domain was using an improper index which was causing it to address memory outside of the current page. Code has been updated to fix the indexing when stepping through the IVL members.
     
  • ABENDHTT001 HCPIVC+16E8 with 16 members in an IVL domain
    Code has been updated to fix an error with VM66907 that was improperly discerning the difference between a transient port number and a reserved port number.
7.4 0304 20260213February 13, 2026 Fix pack No No Yes VM66912 UM90586 z/VM 7.4 CP Fix Pack - Feature 03 Fix 04
  • List-directed IPL causes DEV keyword to be missing from INDICATE USER
    List directed IPL processing has been updated to turn on a bit signifying IPL from a device. This bit is later used by INDICATE USER to output the DEV keyword in the command response.
     
  • Incorrect count of shared APVIRT crypto resources via the SYSTEM CONFIG statement
    The fix skips incrementing the shared crypto resource count if the resource is already included in the shared pool.
     
  • PEVM66887 HCP1010W Loaded when IPLing with SYSG Console
    HCPARM has been changed to correctly set the bits to indicate that the CONS=SYSG IPL parameter was found and this change fixes the HCP1010W wait state problem.
7.4 0303 20251218December 18, 2025 Fix pack No No No VM66907 UM90575 z/VM 7.4 CP Fix Pack - Feature 03 Fix 03
  • ABENDHTT001 HCPXSS+11E0 via the AT command
  • GUEST RELOCATION FAILS WITH HCPRLX1937E RC=3034-03
  • ISFC message loss may cause link/logon/logoff hang in SSI
7.4 0302 20251225December 3, 2025 Hot fix No Yes No VM66903 UM90572 z/VM 7.4 CP Security APAR - Feature 03 Fix 02
7.4 0301 20251125November 25, 2025 Fix pack No No No VM66887 UM90571 z/VM 7.4 CP Fix Pack - Feature 03 Fix 01
  • ABENDHTT001 HCPVIT+374 purging tracks from MDCACHE
  • Paths grouped for offline secondary PPRC devices
  • CPSYNTAX improperly handles entries with leading zero slots
  • FCP cannot be detached after adding a path with an incorrect LUN
  • FLASHCOPY VDEV causes Metro Mirror suspend
  • Console override may fail when using SYSG in IPLPARMS
  • ABENDFRE001 obtaining storage for message buffer length < 0
  • Error code =106 when re-adding a path to an EDEVICE
  • PEVM66877 Dev init fails with conflict error 2nd level
7.4 0300 20251003October 3, 2025 Feature pack No No No VM66877 UM90555 z/VM 7.4 CP Feature Pack - Feature 03 Fix 00
  • EQDIO vNIC Simulation
    Support is provided for creating simulated EQDIO adapters (via DEFINE NIC or NICDEF) and coupling them to a virtual switch operating in QDIO ETHERNET mode. Simulated EQDIO adapters and simulated QDIO adapters can coexist on the same virtual switch.
    November 25, 2025 Update: Guest z/VM systems can experience device initialization errors on certain configurations using simulated devices. These devices may receive the message:
     
    HCPIIO6284I Device nnnn cannot be varied online due to conflicting device classification information.
     
    This has been fixed in the z/VM 7.4 CP Fix Pack 0301.
     
  • EQDIO Multi-VSWITCH Link Aggregation
    Support is provided for using EQDIO adapters in a Multi-VSWICH Link Aggregation configuration.
     
  • Move CMMA Reset Off Master Processor
    The CMMA reset has been changed to avoid the reset entirely for a guest that is not using CMMA. If a reset is required, it will run on a non-Master processor if one is available. The duration of the reset will still be a function of the size of guest memory, but work that must run on the Master processor will not be delayed.
     
  • Soft Abend Improvements
    The feature will allow clients to prevent soft ABENDs from being converted to hard ABENDs and also to limit the number of soft ABEND dumps that can be produced.
     
  • Fast LOGOFF Control
    This feature adds configuration statement and command support to allow the "fast" LOGOFF action delivered by APAR VM66673 to be turned off. This will enable customers to prevent guests from logging back on before they have released their memory resources.
7.4 0203 20250904September 4, 2025 Fix pack No No Yes VM66871 UM90552 z/VM 7.4 CP Fix Pack - Feature 02 Fix 03
  • Vary on hang for DASD with conflicting device IDS
    A new flag and associated internal branch logic was added to break out of the retry loop in the case of conflicting device information, within the VARY ON processing of the real device initialization process.
     
  • Coupling facility simulation fails to copy full buffer list
    A 64 bit address is initially loaded with LG, but then later compared using an LTR instruction. when the low word is 0, it assumes the entire 64 bit value is 0. The fix changed the LTR to LTGR and now properly compares the guest address.
7.4 0202 20250820August 20, 2025 Fix pack No No Yes VM66866 UM90549 z/VM 7.4 CP Fix Pack - Feature 02 Fix 02
  • TDMF receives RC 2 on Diagnose x98 Lock request
  • FLASHCOPY error on compression-enabled target drive
  • Transfer of spool file corrupts the originator ID
  • System failure in module HCPNVM tracing PCIe event
7.4 0201 20250618June 30, 2025 Fix pack No No Yes VM66854 UM90538 z/VM 7.4 CP Fix Pack - Feature 02 Fix 01
  • Error message HCPSWU2832E incorrect for OSH device
  • IQG001 abend when CSCH takes too long
  • Packet and Byte counters for EQDIO incorrect on Q VSWITCH
  • QDIO throughput fields go to 0 in PERFKIT
  • Traffic not flowing across Hipersockets guest LAN
  • HCP3228I sometimes shows 0000 for device address
  • Code was added to take a channel log on VQF002 abends. This log can be used by hardware service personnel to better debug QDIO errors while running under QIOASSIST.
7.4 0200 20250618June 18, 2025 Hardware support No No No VM66824 UM90512 z/VM 7.4 CP Hardware Support - Feature 02 Fix 00
  • IBM z17 Support and Exploitation
    GA1 processor compatibility, EQDIO, and new IBM z17 device support, and ME1 / ML1 VMHCD and VMHCM support for z/VM 7.4 (HCD Requires z/CMS and z/XC support).
     
    Note: RACF users must install RACF 0100 (APAR VM66858) together with this CP z17 Hardware Support APAR. See June 20 z/VM Service Red Alert for more information.
7.4 0102 20250605June 5, 2025 Fix pack Fixed No Yes VM66844 UM90528 z/VM 7.4 CP Fix Pack - Feature 01 Fix 02
PE Corrected with this Fix Pack
  • Transactional Execution Disablement and Use Discovery
    This new function can be exploited to detect applications that use the Transactional Execution Facility.
     
  • A LOGOFF delay may prevent SSI LOGOFF notification
    Code has been changed to ensure that notifications are sent correctly.
     
  • Defects in SCSI alternate device support
    Duplicate alternate device definition checking has been improved to ensure that duplicates are detected and reported correctly.
     
  • FOR command causes CNF001 Soft ABEND
    Command response handling has been corrected to ensure that FOR command responses are delivered as expected.
     
  • PRG004 if invalid buffer length provided to Diagnose 26C
    Hiper related - Code has been changed to validate the Diagnose 26C buffer length.
     
7.4 0101 20250502May 2, 2025 Fix pack Yes No Yes VM66839 UM90524 z/VM 7.4 CP Fix Pack - Feature 01 Fix 01
Update May 6, 2025 - Critical PE introduced with this fix pack.
  • INCORRECT OUTPUT FROM DIAG26C SUBCODE 20
    Diagnose 26c subcode 20 for response formats 0000 0001 thru 0000 0005 can return VSWITCH information structures with an incorrect structure counter. To resolve the problem, the improper return code and possible hanging pointer were addressed.
    May 6, 2025 Update: A critical PE has been found due to this change.
     
  • ACTIVE SERVER ON VSWITCH WITH HIGH RX DISCARD RATE
    Additional conditions are established to determine whether VSWITCH should discard packets waiting to be delivered to a guest.
     
  • UNEXPECTED FORCE ARCH REQUIRED FOR LGR
    The setting of a default architectural value in system initialization was reset to a previous value. This prevents virtual machine relocation from failing due to architecture incompatibility checks.
     
  • VARIOUS ABENDS SYSTEM ITERATOR SERIALIZATION ISSUE
    Hiper related - The iterator was updated to check the HDPBK for table level information instead of checking the first STE in the ST for the table level information. This avoids making the wrong decision if serialization is held on the first STE.
     
  • PRG004 ABENDS
    Hiper related - A missing parameter was added to a subroutine call.
     
7.4 0100 20250403April 3, 2025 Feature pack No No No VM66829 UM90510 z/VM 7.4 CP Feature Pack - Feature 01 Fix 00
  • TRSOURCE IO 5-Digit Device Support
    Extends TRSOURCE support to 5-digit device addresses, which comprise a subchannel-set (SS) number concatenated to the left of the device address. This applies only to real device addresses and therefore to the operand of the TRSOURCE command RDEV keyword. This support has also been added to the DVF component and is available in APAR VM66830.
     
  • Two-Speed Monitoring
    Two-Speed Monitoring provides a mechanism for collecting z/VM Monitor data at two different sampling rates. This avoids disrupting existing client processes that rely on Monitor data collection.
     
7.4 0008 20250325March 14, 2025 Fix pack No No Yes VM66831 UM90506 z/VM 7.4 CP Fix Pack - Feature 00 Fix 08
  • System Hang Due to MDC Consuming Less than 2G Storage
    Logic is added to consumers of MDC frames to examine the ratio of MDC frames <2G to >2G and if skewed <2G then attempt to get a FRMTE conditionally from the >2G available zones. If this request fails, then the old path is used. This ensures a balance of MDC frames and no loop possible.
     
7.4 0007 20250225February 25, 2025 Fix pack No No Yes VM66821 UM90503 z/VM 7.4 CP Fix Pack - Feature 00 Fix 07
  • Unable to Detach CPOWNED Volume Marked Shared
    The logic to dictate whether a device can be detached or not based on CSE sharing still exists, causing unexpected denial of a DETACH command. This fix removes the check and prevents the DETACH denial when a non-SSI system attached device finds itself with spool extents that are not owned by its system.
     
7.4 0006 20250131January 31, 2025 Fix pack No No No VM66819 UM90502 z/VM 7.4 CP Fix Pack - Feature 00 Fix 06
  • Guest Relocation Incompatibility
    Internal handling of the architected value of interest was updated to prevent the relocation errors related to potential architectural incompatibility introduced to the guest.
    March 20, 2025 Update: When fix is applied in an SSI, "FORCE ARCH" is still required for relocations.
     
  • Unplanned Hyperswap on Subchannel Offline Device
    To ensure this incorrect HyperSwap trigger no longer occurs, a set of changes were made to improve the CC3 error recovery path and prevent subchannel offline (SUBCHOFF) devices from persisting in a GDPS environment enabled for HyperSwap auto-quiesce.
     
  • PRG006 Encountered Due to Improper Instruction Input
    Once it was discovered the wrong input was being passed to the failing instruction, the input was fixed. The problem situation was recreated with and without the fix to ensure the abend was avoided.
     
7.4 0005 20241218December 18, 2024 Hot fix Fixed No Yes VM66815 UM90496 z/VM 7.4 CP Hot fix - Feature 00 Fix 05
  • PE Corrected with this Fix Pack
    This fix removes the "System Hang Due to MDC Consuming Less Than 2G Storage" code that was part of fix pack 0004 and restores the previous function.
7.4 0004 20241014October 14, 2024 Fix pack Yes No No VM66800 UM90483 z/VM 7.4 CP Fix Pack - Feature 00 Fix 04
Update Nov. 25, 2024 - PE introduced with this fix pack.
  • System Hang Due to MDC Consuming Less Than 2G Storage
    Logic was added to subroutine HCPPTG:GetFRMTEs that will rebalance the distribution of MDC data frames by looking at the current distribution and preferring frames >2G when the current distribution is skewed toward <2G memory.
    November 19, 2024 Update: A critical PE has been found due to the change in the HCPPTG:GetFRMTEs subroutine. A MCW002 ABEND may occur during normal systems operation (replenishment of the uncleared local available lists) on a system that is paging or near paging.
     
  • RDM024 ABEND After Clearing SSI Slot With Dummy ARD
    The ARD comparison routine was changed to give the correct equality result when two dummy ARDs are compared.
     
  • PEVM66675 Missing Interrupt for Dedicated PCI Function
    PCI function interrupt processing code was modified to not alter adapter interrupt summary bits for dedicated PCI functions. This will prevent missing interrupts for the owning guest.
     
  • ABENDLCK001 HCPLCK+DC8 After NVME EDEV Lost
    An incorrect invocation of the z/VM interrupt handler for NVMe EDEVICES was used when the interruption presented for the PCI Function removal was received. This call to the NVMe interrupt handler has been corrected.
7.4 0003 20240928September 28, 2024 Fix pack No No Yes VM66796 UM90478 z/VM 7.4 CP Fix Pack - Feature 00 Fix 03
  • SXA004 ABEND (ABENDSXA004) caused by the CP CHANGE or CP TRANSFER Commands
    Hiper related - Because the DVMD is only needed for the ESM call, the DVMD is obtained only in the case when that ESM call is needed. To ensure that the conditional obtain and release of the DVMD are in agreement, a test is added to HCPSCO subroutine FINDUSER to call HCPUDRFU instead of HCPUDRGU when the protect flags are on but the TRANSFER or CHANGE came in as a cross-system command.
     
  • CP SPOOL Processing Causes DirMaint Message Flood
    Code has been added to HCPXTPCK to update SPFBRDBT when the SPFBBITS field is updated prior to calling the routines to update the copy systems.
     
  • VARY Hangs After Unplanned Hyperswap
    PPRC/Metro Mirror suspension recovery was updated to reset the associated control unit quiesce condition as soon as possible and then complete the remainder of the associated recovery. This reduces the potential for other processes to be delayed by the pending PPRC suspend recovery process.
7.4 0002 20240920September 20, 2024 Hot fix No Yes No VM66795 UM90474 z/VM 7.4 CP Security APAR - Feature 00 Fix 02
7.4 0001 20240920September 20, 2024 Fix pack No No Yes VM66780 UM90463 Initial fix pack that is provided with the z/VM 7.4 GA installation media.
  • ABEND PRG004 in ISFC Timeout Processing
    ISFC Serialization was expanded to account for the potential interaction between the Link I/O layer and message queue handling which led to the abend.
     
  • MAC Table Synchronization Errors Following VMRELOCATE
    SSI communication used to indicate changes in MAC address usage was updated to ensure the guest LOGOFF case builds a valid request which will update the MAC tables on all members of the SSI.
     
  • ABEND PRG004 in HCPSWL for Multi-VSWITCH LAG Configurations
    The processing of the state change notification received from the OSA adapter was updated to verify the network connection for the port is still operational before attempting recovery. If the port is no longer operational, there is no need to process the state change and it will be discarded.
     
  • XFS File System Errors After HPF I/O to Virtual HyperPAV Alias
    HPF I/O translation was updated to ensure internal control block structures for virtual HyperPAV aliases are updated prior to I/O translation. This ensures the I/O requests are now always translated correctly for the current alias usage.