Re: nvmm Intel minimum requirements

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 17/02/2019 à 20:35, Jared McNeill a écrit :
> On Sun, 17 Feb 2019, Jared McNeill wrote:
> > What are the min requirements for the Intel nvmm backend? I upgraded my
> > Thinkpad T420 to -current today to try it and it says no backends are
> > available. CPU is i5-2520M, and HAXM works OK on it.
>
> I added some printfs to the module, and this test is what fails:
>
>          if ((msr & IA32_VMX_EPT_VPID_FLAGS_AD) == 0) {
>                  return false;
>          }

That means your cpu does not support EPT_A and EPT_D (pmap.c).

As you probably saw in vmx_ident(), on Intel there is a ton of checks to
detect the CPU support, and it was hard for me to tell which feature was
common and which feature was rare.

So I developed the pmap code considering that the AD flags would be
there. Looking at the code, I think we can easily drop AD completely,
and remove this requirement.

I will do that.