How To
Summary
The POWER9™ based IBM Power Systems™' range offer a number of different Processor Compatibility modes. This document explains them.
Objective
Environment
Compatibility Mode
This field displays the processor mode for this logical partition. A processor compatibility mode is a value assigned to a logical partition by the hypervisor that specifies the processor environment in which the logical partition can successfully operate. Also, processor compatibility modes enable you to move logical partitions between servers that have different processor types without upgrading the operating environments installed in the logical partitions.
Depending on the capabilities of your managed system and the operating system of the logical partition, the processor compatibility mode can be one the following values:
- Default (default)
-
This is the preferred processor compatibility mode that enables the hypervisor to determine the current mode for the logical partition. The current mode will be the most fully-featured mode supported by the operating system on the logical partition. You can specify default as the preferred processor compatibility mode. Also, if you do not specify a preferred mode, the system automatically sets the preferred mode to default.
In most cases, this is the processor type of the server on which the logical partition is activated. For example, assume that the preferred mode is set to default and the logical partition is running on a POWER7 processor-based server. The operating environment supports the POWER7 processor capabilities so the hypervisor sets the current processor compatibility mode to POWER7.
- POWER9 Base
- The operating system version on the logical partition is set to use all the standard features of the POWER9 processor enabled by the firmware at level FW910. Logical partitions that use the POWER9_Base processor compatibility mode can run on POWER9 processor-based servers running firmware at level FW910, or later.
- POWER8
- The operating system version on the logical partition is set to use all the standard features of the POWER8 processor. The logical partitions that use the POWER8 processor compatibility mode can run on POWER8 processor-based servers. If the system's processor compatibility mode is lower than POWER8, the POWER8 option is not available in the list. By using the Live Partition Mobility function, a logical partition with lower processor modes than POWER8 can be migrated to the POWER8 systems.
- POWER7
- The operating system version on the logical partition is set to use all the standard features of the POWER7 processor. Logical partitions that use the POWER7 processor compatibility mode can run on POWER7 and POWER8 processor-based servers. The POWER7 processor-based servers do not support the enhanced mode.
The processor compatibility mode used by a logical partition depends on the following information:
- The processor compatibility mode setting on the partition profile that you use to activate the logical partition
- The processor compatibility modes that are supported by the operating system or system software that is installed on the logical partition
When you activate a logical partition, the managed system checks the processor compatibility mode setting on the partition profile, and determines whether the installed operating system or system software supports the specified mode. If so, the logical partition uses the processor compatibility mode from the partition profile. If not, the logical partition uses the most fully featured mode that is supported by the installed operating system or the system software.
You cannot dynamically change the current processor compatibility mode of a logical partition. To change the current processor compatibility mode, you must change the preferred processor compatibility mode, shut down the logical partition, and restart the logical partition. The hypervisor then attempts to set the current processor compatibility mode to the preferred mode that you specified.
If the operating environment installed in the logical partition does not support the preferred mode, the hypervisor can set the current mode to a lower mode than the preferred mode, but it cannot set the current mode to a higher mode than the preferred mode. For example, assume that a logical partition runs on a POWER9 processor-based server with firmware at level FW910 and you specify POWER9 Base as the preferred mode. The operating environment installed in the logical partition does not support the POWER9 Base processor capabilities, but it does support the POWER8 processor capabilities. When you activate the logical partition, the hypervisor assigns the POWER8 processor compatibility mode as the current mode for the logical partition because the POWER8 mode is the most fully featured mode that the operating environment supports and it is a lower mode than the preferred mode of POWER9 Base.
- User Mode NX Accelerator Enablement for PowerVM. This enables the access of NX accelerators such as the gzip engine through user mode interfaces. The IBM Virtual HMC (vHMC) 9.1.940 provides a user interface to this feature. The LPAR must be running in POWER9 compatibility mode to use this feature. For more information on compatibility modes, see the following two articles in the IBM Knowledge Center:
- Support for SR-IOV logical ports in IBM i restricted I/O mode.
- Support for user mode enablement of the External Interrupt Virtualization Engine (XIVE). This user mode enables the management of interrupts to move from the hypervisor to the operating system for improved efficiency. Operating systems may also have to be updated to enable this support. The LPAR must be running in POWER9 compatibility mode to use this feature. For more information on compatibility modes, see the following two articles in the IBM Knowledge Center:
- Extended support for PowerVM Firmware Secure Boot. This feature restricts access to the Open Firmware prompt and validates all adapter boot driver code. Boot adapters, or adapters which may be used as boot adapters in the future, must be updated to the latest microcode from IBM Fix Central. The latest microcode will ensure the adapters support the Firmware Secure Boot feature of Power Systems. This requirement applies when updating system firmware from a level prior to FW940 to levels FW940 and later. The latest adapter microcode levels include signed boot driver code. If a boot-capable PCI adapter is not installed with the latest level of adapter microcode, the partition which owns the adapter will boot, but error logs with SRCs BA5400A5 or BA5400A6 will be posted. Once the adapter(s) are updated, the error logs will no longer be posted.
- Linux OS support was added for PowerVM LPARs for the PCIe4 2x100GbE ConnectX-5 RoCE adapter with feature codes of #EC66/EC67 and CCIN 2CF3. Linux versions RHEL 7.5 and SLES 12.3 are supported.
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Modified date:
02 July 2020
UID
ibm16243336