Processor Compatibility Mode

This field displays the processor mode for this logical partition. The processor mode determines which processor features are available to the logical partition.

Valid values are:

POWER6 or default

The logical partition is set to use POWER6 architected processor mode, or the operating system version installed on the logical partition does not support POWER6 enhanced processor mode.

POWER6_Enhanced

The logical partition is set to use POWER6 enhanced processor mode. POWER6 enhanced processor mode provides additional floating point instructions to applications running on the logical partition.

POWER5

The operating system version installed on the logical partition supports POWER5 processor modes but does not support POWER6 processor modes.

The processor compatibility mode used by a logical partition depends upon the following:

• The partition compatibility mode setting on the partition profile that you use to activate the logical partition
• The partition compatibility modes that are supported by the operating system or system software that is installed on the logical partition

Each partition profile has a partition compatibility mode setting. By default, partition profiles for POWER6 systems are set to the POWER6 architected processor mode. You can set the processor compatibility mode of a partition profile to the POWER6 enhanced mode by using the HMC command chsyscfg -r prof to set the lpar_proc_compat_mode attribute to enhanced. If you want to set the processor compatibility mode of a partition profile back to the POWER6 architected mode, use the HMC command chsyscfg -r prof to set the lpar_proc_compat_mode attribute back to default. (You cannot set a partition profile to the POWER5 compatibility mode.)

When you activate a logical partition, the managed system checks the partition 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 partition 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 system software. (The logical partition therefore cannot use a more fully featured mode than the mode specified on the partition profile, but the operating system or system software can negotiate a lesser mode if it does not support the mode specified on the partition profile.)

You cannot dynamically change the partition compatibility mode used on a logical partition. To change the partition compatibility mode, you must shut down the logical partition and restart the logical partition with a partition profile that is set to the desired partition compatibility mode.

A POWER6 processor cannot emulate all features of a POWER5 processor. For example, certain types of performance monitoring might not be available for a logical partition if the logical partition is set to the POWER5 compatibility mode.

This field displays only if the managed system uses POWER6 processors and is capable of setting partition processor capability modes.