Even more fun is that some of those (IOMMU and ACPI version) depend on motherboard/firmware support. Inevitably there is some bargain-bin board for each processor generation that doesn’t support anything that isn’t literally required for the CPU/chipset to POST. For userspace CPU features the new x86_64-v3/v4 profiles that Clang/LLVM support are good Schelling points, but they don’t cover e.g. page table features.

Windows has specific platform requirements they spell out for each version - those are generally your best bet on x86. ARM devs have it way worse so I guess we shouldn’t complain.

At least on ARM you can get trms or data sheets that cover all of the features of a specific processor and also the markings on the chip that differentiate it from models within the same family.