Effective and configured processor compatibility modes
The processor compatibility mode in which the logical partition currently operates is the effective processor compatibility mode of the logical partition. The configured processor compatibility mode of a logical partition is the mode in which you want the logical partition to operate.
The hypervisor sets the effective processor compatibility mode for a logical partition by using the following information:
- The processor features supported by the operating environment running in the logical partition.
- The configured processor compatibility mode that you specify.
When you activate the logical partition, the hypervisor checks the configured processor compatibility mode and determines whether the operating environment supports that mode. If the operating environment supports the configured processor compatibility mode, the hypervisor assigns the logical partition the configured processor compatibility mode. If the operating environment does not support the configured processor compatibility mode, the hypervisor assigns the logical partition the most fully featured processor compatibility mode that is supported by the operating environment.
The following table describes when each processor compatibility mode can be effective mode or the configured mode.
| Processor compatibility mode | Can it be the effective mode? | Can it be the configured mode? |
|---|---|---|
| POWER7® | Yes The POWER7 processor compatibility mode can be the effective processor compatibility mode of a logical partition. |
Yes You can specify POWER7 as the configured processor compatibility mode for a logical partition. |
| POWER8® | Yes The POWER8 processor compatibility mode can be the effective processor compatibility mode of a logical partition. |
Yes You can specify POWER8 as the configured processor compatibility mode for a logical partition. |
| POWER9™ Base | Yes The POWER9 Base processor compatibility mode can be the effective processor compatibility mode of a logical partition. |
Yes You can specify POWER9 Base as the configured processor compatibility mode for a logical partition. |
| POWER9 | Yes The POWER9 processor compatibility mode can be the effective processor compatibility mode of a logical partition. |
Yes You can specify POWER9 as the configured processor compatibility mode for a logical partition. |
| default | No The default processor compatibility mode is a configured processor compatibility mode. |
Yes You can specify default as the configured processor compatibility mode. Also, if you do not specify a configured mode, the system automatically sets the configured mode to default. |
The configured processor compatibility mode is the highest mode that the hypervisor can assign to a logical partition. If the operating environment installed in the logical partition does not support the configured mode, the hypervisor can set the effective mode to a lower mode than the configured mode, but it cannot set the effective mode to a higher mode than the configured 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 configured 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 effective 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 configured mode of POWER9 Base.
The configured processor compatibility mode is the highest mode that the hypervisor can assign to a logical partition. If the operating environment installed in the logical partition does not support the configured mode, the hypervisor can set the effective mode to a lower mode than the configured mode, but it cannot set the effective mode to a higher mode than the configured mode. For example, assume that a logical partition runs on a POWER9 processor-based server with firmware at level FW940 and you specify POWER9 as the configured mode. The operating environment installed in the logical partition does not support the POWER9 processor capabilities, but it does support the POWER9 Base processor capabilities. When you activate the logical partition, the hypervisor assigns the POWER9 Base processor compatibility mode as the effective mode for the logical partition because the POWER9 Base mode is the most fully featured mode that the operating environment supports and it is a lower mode than the configured mode of POWER9.
You cannot dynamically change the effective processor compatibility of a logical partition. To change the effective processor compatibility mode, you must change the configured processor compatibility mode, shut down the logical partition, and restart the logical partition. The hypervisor attempts to set the effective processor compatibility mode to the configured mode that you specified.
When you migrate an active logical partition between servers with different processor types, both the effective and configured processor compatibility modes of the logical partition must be supported by the destination server. When you migrate an inactive logical partition between servers with different processor types, only the configured mode of the logical partition must be supported by the destination server.
If you specify the default mode as the configured mode for an inactive logical partition, you can migrate that inactive logical partition to a server of any processor type. Because all servers support the default processor compatibility mode, you can migrate an inactive logical partition with the configured mode of default to a server with any processor type. When the inactive logical partition is activated on the destination server, the configured mode remains set to default, and the hypervisor determines the effective mode for the logical partition.