Summary of Changes for z/VM: CP Commands and Utilities Reference

Miscellaneous updates for October 2025

[7.3 VM66878] Enhanced QDIO virtual switch vNIC simulation

With the PTF for APAR VM66878 (CP), z/VM 7.3 provides guests with the ability to define simulated enhanced QDIO (EQDIO) network interface cards (vNICs) on the virtual switch. With this support, a guest has the option to establish and activate a network connection in either traditional QDIO or EQDIO mode. QDIO mode requires three devices to activate a network connection but EQDIO mode requires only a single device.

[7.3 VM66850] Transactional execution disablement

With the PTF for APAR VM66850 (CP), z/VM 7.3 provides support for transactional execution disablement. This support introduces a way to test application migration and detect usage of the transactional-execution facilities with z/VM 7.3, thus preparing z/VM 7.3 users for the eventual reduction and removal of support for these facilities.

Miscellaneous updates for September 2025

[7.3 VM66823] z/VM support for the IBM z17 family

With the PTFs for APARs VM66823 and VM66853 (7.3 CP) and VM66857 (7.3 RACF), z/VM 7.3 provides support for the IBM® z17® family. For more information, see z/VM support for the IBM z17 family in the z/VM: Migration Guide.

[VM66746] QUERY DASD DETAILS command is updated to allow I/O to be issued for a user when QUICKDSP is set on

With the PTF for APAR VM66746, the QUERY DASD DETAILS command is updated to allow I/O to be issued for a user when QUICKDSP is set on. Previously, information about the fenced state and host access would not be displayed in the Q DASD DETAILS output. A usage note and a response that indicates the previous restrictions are removed from documentation of the QUERY DASD command.

[VM66749] Relax SCSI alternate path restrictions

With the PTF for APAR VM66749, the uniqueness requirement for the DEVICE fcp_vdev operand of the LOADDEV user directory statement and the SET LOADDEV and SET DUMPDEV commands is relaxed. Previously, the device number was required to be unique from any device numbers that were specified in any ALTERNATE path definitions. When the PTF is applied, the combination of device number and port name must be unique from those specified in any ALTERNATE path definitions.

[VM66742] VSwitch recovery logic is updated to eliminate endless recovery attempts

With the PTF for APAR VM66742, the VSwitch recovery logic is updated. When a device reset and re-initialization of a VSwitch Uplink Port does not clean up an error condition after multiple attempts, the VSwitch recovery logic now stops its device recovery attempts and issues message HCP3233E.

Miscellaneous updates for June 2024

[VM66758, VM66759] SCP identification enhancements

With the PTF for APAR VM66758, the z/VM Control Program (CP) can display identification information that is provided by guest operating systems. The CP display is similar to the HMC Systems Management "Partitions" display. SCP identification enhancements provide a means to determine what operating system a guest is running and also what guest operating systems have identified themselves since the z/VM system last IPLed.

With the PTF for APAR VM66759, z/VM's Control Monitor System (CMS) is enhanced. A user can change the CMS system identification information that a guest sends to the hypervisor.

Miscellaneous updates for March 2024

[VM66726] MONWRITE CLOSE Enhancements

With the PTF for APAR VM66726, the z/VM 7.3 MONWRITE command can specify the file mode for the monitor files it produces when the CLOSE option is specified. Previously, the command could specify the mode of the monitor file or the CLOSE option but not both.

[VM66727] FCP SCSI List-directed IPL alternate paths

With the PTF for APAR VM66727, z/VM 7.3 provides the ability to specify alternate paths for list-directed SCSI IPL. If IPL fails for the primary device path, alternate device paths are used automatically. The new ALTERNATE operand of the SET DUMPDEV and SET LOADDEV commands and the LOADDEV directory statement can specify up to three alternate device paths. The responses to the QUERY DUMPDEV and QUERY LOADDEV commands indicate the alternate device paths.

[VM66678, VM66709] Warning Track Interruption Facility

With the PTFs for APARs VM66678 (CP) and VM66709 (Performance Toolkit), z/VM 7.3 exploits a feature of Processor Resource/Systems Manager (PR/SM) called the warning-track-interruption facility. z/VM's exploitation of this facility helps improve guest response time and overall performance of workloads that are run on vertical-low or vertical-medium logical processors.

[VM66673] Information update about Large Guest Reset Time Mitigation

[VM66683] Channel Path Usage

[VM66423] Crypto Stateless-Command Filtering

With the PTF for APAR VM66423, z/VM 7.3 provides support for a capability of the Crypto Express8S adapter, when configured in Common Cryptographic Architecture (CCA) coprocessor mode, to enforce restrictions on classes of requests. This support is intended to be used to limit operations on shared crypto resources, such as prohibiting secure-key functions. z/VM’s exploitation of this hardware capability will replace the crypto stateless command filtering performed by z/VM for APVIRT crypto users, thus eliminating the need for future z/VM updates to allow stateless CCA operations beyond those currently supported. The z/VM hypervisor specifies the policy, and the Crypto Express8S adapter enforces it. Crypto Stateless-Command Filtering requires an IBM z16® family server with driver D51C Bundle S19 applied.

[VM66423] Removal of obsolete IOCP Parameters DYN and NODYN

With the PTF for APAR VM66423, the IOCP parameters DYN and NODYN, which previously allowed or prevented dynamic changes to I/O configurations, no longer have any effect.

[VM66424, VM66434, VM66650] Guest Secure IPL Support

With the PTF for APARs VM66424, VM66434, and VM66650, z/VM V7.3 supports guest secure IPL (load and dump) for both ECKD and SCSI devices. A z/VM user can request that the machine loader validate the signed IPL code by using the security keys that were previously loaded by the customer into the HMC certificate store. The validation ensures that the IPL code is intact, unaltered, and originates from a trusted build-time source.

z/VM and the z/VM stand-alone dump utility do not support performing host IPL via List-Directed IPL (LD-IPL) from ECKD. In addition, Secure IPL of the z/VM host and z/VM stand-alone dump are not supported.

[VM66654] Thin Stack Adapter Interrupt Support

With the PTF for APAR VM66654, z/VM 7.3 enhances the Thin Stack FCP SCSI device driver and associated I/O abstraction layers to exploit adapter interruptions and to implement improved error handling and reporting.

[VM66673] Large Guest Reset Time Mitigation

With the PTF for APAR VM66673, z/VM 7.3 provides support for up to 2TB virtual memory within a single virtual machine under a set of restrictions while also providing a mitigation for long logoff times of guests with a large amount of instantiated virtual memory.

[VM66675] Enable larger (>64GB) NVMe paging allocation extents

With the PTF for APAR VM66675, z/VM 7.3 allows paging space to be allocated anywhere on an NVMe EDEVICE and to be of any size up to the available capacity. This PTF also adds the ability for the CPFMTXA utility to accept FBA allocations specified in factors of megabytes, gigabytes, and terabytes.

See CPFMTXA.

This support requires the corresponding ICKDSF PTF for APAR PH52513, which removes the 64G restriction for PAGE allocation on an FBA volume.

[VM66677] Increase crashkernel area size

With the PTF for APAR VM66677, z/VM 7.3 increases the size of crashkernel area allocated by stand-alone dump programs in preparation for a future enhancement.

Miscellaneous updates for May 2023

Eight-member SSI support

This support increases the maximum size of a single system image (SSI) cluster from four members to eight, enabling clients to grow their SSI clusters to allow for increased workloads and providing more flexibility to use live guest relocation (LGR) for nondisruptive upgrades and workload balancing.

NVMe emulated device (EDEVICE) support

NVMe devices that are connected through PCI Express (PCIe) adapters can be defined and managed as Fixed-Block Architecture (FBA) EDEVICEs. As such, all host and guest FBA functions are supported except for those functions that require stand-alone support such as warm start and checkpoint. Linux guests that exploit EDEVICEs that are defined on NVMe adapters are not eligible for live guest relocation. NVMe adapters are only available on IBM LinuxONE servers. For more information, see Defining and Managing NVMe Devices.

Display mnemonics for instructions that are not supported by CP Trace

Miscellaneous updates for z/VM 7.3