Function __cpuid_count

pub unsafe fn __cpuid_count(leaf: u32, sub_leaf: u32) -> CpuidResult

Available on x86 and (x86 or x86-64) only.

Returns the result of the cpuid instruction for a given leaf (EAX) and sub_leaf (ECX).

The highest-supported leaf value is returned by the first tuple argument of __get_cpuid_max(0). For leaves containung sub-leaves, the second tuple argument returns the highest-supported sub-leaf value.

The CPUID Wikipedia page contains how to query which information using the EAX and ECX registers, and the interpretation of the results returned in EAX, EBX, ECX, and EDX.

The references are:

• Intel 64 and IA-32 Architectures Software Developer’s Manual Volume 2: Instruction Set Reference, A-Z.
• AMD64 Architecture Programmer’s Manual, Volume 3: General-Purpose and System Instructions.