Method and Apparatus For Selecting the Architecture Level to Which a Processor Appears to Conform

A processor, comprising:

• at least one execution unit;
• a processor compatibility register (PCR) specifying an architecture level to which the processor is to appear to conform during execution of a particular program;
• logic for selecting the current architecture level to which the processor appears to conform, said logic comprising logic for:
• setting a value of one or more bits within a processor compatibility register (PCR) within the processor, said value corresponding to an architecture level to which the processor is to appear to conform during subsequent execution of a logical partition or program;
• and
• automatically configuring the processor to appear to conform to a particular architecture level, based on the value of the one or more bits within the PCR.

A data processing system comprising:

• a memory having therein code for executing a super-privileged client during a super-privileged state of operation;
• a processor coupled to the memory via an interconnect, said processor having:
• at least one execution unit;
• a processor compatibility register (PCR) specifying an architecture level to which the processor is to appear to conform during execution of a particular program;
• logic for selecting the current architecture level to which the processor appears to conform, said logic comprising logic for:
• setting a value of one or more bits within a processor compatibility register (PCR) within the processor, said value corresponding to an architecture level to which the processor is to appear to conform during subsequent execution of a logical partition or program;
• and
• automatically configuring the processor to appear to conform to a particular architecture level, based on the value of the one or more bits within the PCR.