Highest valid sub-leaf index of CPUID(EAX = 0DH)

[JWong19]

I refer to the document of ISA extensions at <https://software.intel.com/sites/default/files/managed/07/b7/319433-023.pdf>. (page 2-18)

The highest valid sub-leaf index, n, is

(POPCNT(CPUID.(EAX=0D, ECX=0):EAX) + POPCNT(CPUID.(EAX=0D, ECX=0):EDX) - 1)

How to obtain this formula of the highest valid sub-leaf index of CPUID.0DH?

I expect that it should be the most-significant bit of CPUID.(EAX=0D,ECX=0).[EAX:EDX] instead, because the sub-leaf index corresponds to bit position of CPUID.(EAX=0D,ECX=0).[EAX:EDX]

[MarkC_Intel · Accepted solution]

Doc bug. 

I will ask the doc team to try sync the CPUID stuff up again. 

See the latest SDM instead: http://www.intel.com/sdm

[JWong19]

Thanks for confirmation of the bug