AMD Zen 6 low-power cores can no longer be hidden! Linux 7.3 gets early patches: Intel/AMD core types finally unified

The x86/cpu pull request for Linux kernel 7.3 has been merged on August 18. This version brings two significant changes to the x86 architecture: adding recognition support for AMD's upcoming low-power cores, and unifying the CPU core type handling between Intel and AMD.

Linux 7.3 adds the AMD_CPU_TYPE_LOW_POWER identifier to recognize AMD's upcoming low-power cores, allowing the kernel to correctly identify these cores instead of marking them as unknown types.

These low-power cores complement AMD's existing performance cores and efficiency cores, and are expected to be used in some Zen 6 client products. In previous Linux kernels, these cores could function but were only recognized as unknown cores.

More notably, Linux 7.3 maps core type definitions from different vendors into a unified generic core type system. Previously, Intel and AMD each used independent numbering systems, which was highly prone to confusion.

Beyond core type recognition updates, Linux 7.3 also merges several x86 architecture optimizations. These include micro-optimizations targeting hardware from the AMD Athlon XP era:

For older devices that only support SSE but not SSE2, the kernel has switched its write memory barrier code to the SFENCE instruction for improved efficiency; KCFI optimizations for older Intel CPUs; and for MSR register updates, the kernel has stopped using the 32-bit MSR interface, switching entirely to the 64-bit interface, with the 32-bit interface expected to be removed in the Linux 7.4 cycle.

The merge window for Linux 7.3 opened on August 17, and all x86-related updates have now been merged. The version is expected to be officially released in a subsequent cycle.