Crate raw_cpuid

source ·
Expand description

A library to parse the x86 CPUID instruction, written in rust with no external dependencies. The implementation closely resembles the Intel CPUID manual description. The library works with no_std.


use raw_cpuid::CpuId;
let cpuid = CpuId::new();

if let Some(vf) = cpuid.get_vendor_info() {
    assert!(vf.as_str() == "GenuineIntel" || vf.as_str() == "AuthenticAMD");

let has_sse = cpuid.get_feature_info().map_or(false, |finfo| finfo.has_sse());
if has_sse {
    println!("CPU supports SSE!");

if let Some(cparams) = cpuid.get_cache_parameters() {
    for cache in cparams {
        let size = cache.associativity() * cache.physical_line_partitions() * cache.coherency_line_size() * cache.sets();
        println!("L{}-Cache size is {}", cache.level(), size);
} else {
    println!("No cache parameter information available")

Platform support

CPU vendors may choose to not support certain functions/leafs in cpuid or only support them partially. We highlight this with the following emojis throughout the documentation:

  • ✅: This struct/function is fully supported by the vendor.
  • 🟡: This struct is partially supported by the vendor, refer to individual functions for more information.
  • ❌: This struct/function is not supported by the vendor. When queried on this platform, we will return None/false/0 (or some other sane default).
  • ❓: This struct/function is not supported by the vendor according to the manual, but the in practice it still may return valid information.

Note that the presence of a ✅ does not guarantee that a specific feature will exist for your CPU – just that it is potentially supported by the vendor on some of its chips. You will still have to query it at runtime.


  • Uses Rust’s cpuid function from the arch module.


  • Macro which queries cpuid directly.




  • This table is taken from Intel manual (Section CPUID instruction).