[Discuss] How do I check cpu compatibility?

[Daniel M Gessel]

It's nice to be able to optimize SW (at build time) to use some ISA 
extensions, but so many unique subsets of extensions have been realized 
in silicon that it's a bit of a mess. Defining, retrospectively, 
"sub-architectures" around key extensions for OS performance and 
security seems like a good idea.

CPUID can still be used to detect individual extensions at run-time.


On 2023-10-08 10:41, Shankar Viswanathan wrote:
> On 10/8/23 03:01, John Abreau wrote:
>>> I figure Intel  uses terminology other than "x86-64-v2", but I have 
>>> no idea
>>> what their terminology is. None of my google searches have found 
>>> anything
>>> helpful.
>>>
>>> How can I determine whether a given cpu type is "x86-64-v2" compatible?
>
> You have my sympathies! Intel and AMD each use a different terminology 
> and for some reason the software vendors have decided to use yet other 
> confusing names for the same set of features. x86-64 (aka AMD64) 
> itself keeps evolving, but neither AMD nor Intel have established a 
> versioning scheme on the ISA itself, so I personally do not like this 
> "x86-64-v2" naming. The features being discussed here are specific to 
> virtualization support, not the whole ISA. The basic HW virtualization 
> support is called SVM or AMD-V by AMD, and VT-x by Intel.
>
> Broadly, there are two features that have been labeled as "v2" in this 
> context:
> 1. Support for second level address translations (aka SLAT): AMD calls 
> this Nested Page Tables (NPT), and Intel calls it Extended Page Tables 
> (EPT)
> 2. Support for I/O virtualization: AMD calls this IOMMUv2 or AMD-Vi, 
> and Intel refers to this as VT-d
>
> As pointed out in the previous comment, most 
> server/workstation/desktop processors from Intel and AMD have 
> supported these features for at least a decade. There are certain 
> products and SKUs that may not support it (typically only lower end 
> products), so it is best to read the spec summary from AMD or Intel to 
> confirm.
>
> Specific to your question about Xeon E5-2690 V2, see:
> https://www.intel.com/content/www/us/en/products/sku/75279/intel-xeon-processor-e52690-v2-25m-cache-3-00-ghz/specifications.html 
>
>
> If you scroll down to the "Security and Reliability" section, you'll 
> notice that both VT-d and EPT are supported. So you should be good on 
> that front. Often, these features are not enabled by default in the 
> BIOS, so please make sure to turn them on if you intend to run VMs on 
> the machine. Once you're booted into Linux, you can check 
> /proc/cpuinfo or run `lscpu` to verify that the "vmx", and "ept" flags 
> are present (AMD equivalents will be "svm" and "npt").
>
> -Shankar
>
>
>
>
>
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