Intel’s Arrow Lake-H could feature three types of CPU cores according to Linux patch — hybrid designs could get more complex

Intel’s upcoming Arrow Lake-H processors for higher-end notebooks appear set to bring a new level of complexity to their hybrid core architecture. According to an Intel Linux patch noticed by Phoronix, these processors will include not only Lion Cove high-performance cores (P-cores) but also a mix of two types of efficiency cores (E-cores): the next-generation Skymont cores and the current-generation Crestmont cores.  

The Arrow Lake-H series was initially reported to consist solely of Lion Cove P-cores and Skymont E-cores, and its possible that the integration of a third core type could only apply to certain models in the Arrow Lake-H stack — it isn’t unheard of for Intel to carry lower-end prior-gen processors into its newer generations of processors. 

Skymont is based on an all-new E-core microarchitecture that promises to offer substantial performance improvements over Crestmont, the E-core used in the Meteor Lake. However, the latest Linux patch could mean that Arrow Lake H will also incorporate Crestmont cores alongside Skymont, creating a heterogeneous mix of E-cores. This would be a significant shift from previous Intel designs, which typically used a single type of E-core. 

This combination of two different E-core microarchitectures within a single processor lineup is a first for Intel, though the approach is not completely unheard of. Although Intel hybrid platforms have only featured one type of E-core, there is a major catch. Intel’s Core Ultra ‘Meteor Lake’ processors feature two low-power LP Crestment E-cores integrated into the SoC tile and six fully-fledged Crestmont E-cores in the compute tile. 

Arrow Lake’s compute tile is an Intel 20A-based design with gate-all-around RibbonFET transistors and PowerVia backside power delivery. Re-architecting previous-generation Crestmont cores for GAA transistors makes little sense.

The inclusion of both Skymont and Crestmont cores in the Arrow Lake-H family suggests that Intel is exploring new ways to optimize performance and power efficiency, but it is also going to introduce additional complexity for system management and software support. To manage this complexity, new Linux patches have been developed. 

“ArrowLake-H is a specific variant of regular ArrowLake,” Intel’s description of the patch reads. “It shares same PMU features on lioncove P-cores and skymont E-cores with regular ArrowLake except ArrowLake-H adds extra crestmont uarch E-cores. Thus ArrowLake-H contains two different atom uarchs. This is totally different with previous Intel hybrid platforms which contains only one kind of atom uarchs. In this case, it’s not enough to distinguish the uarchs just by core type.” 

These patches are designed to distinguish between the two types of E-cores within Arrow Lake-H processors, using a unique identifier for each core architecture, which allows the operating system to properly allocate tasks to the appropriate cores based on their capabilities. While the patches give us an idea about two different energy-efficient microarchitectures in Arrow Lake-H, they do not disclose whether Crestmont cores are physically located inside the compute tile or somewhere else.