Re: [PATCH v3 08/10] x86/setcpuid: Add kernel option setcpuid

[Dave Hansen]

On 2/4/19 9:49 AM, Thomas Gleixner wrote:
> On Fri, 1 Feb 2019, Fenghua Yu wrote:
>> This option behaves like existing kernel option clearcpuid.
> 
> No it does NOT. clearcpuid allows to disable things.
> 
> This allows to enable random CPUID bits without any sanity checking. Not
> going to happen. We made it clear in the past that functionality needs to
> be detectable by enumeration. We do quirks for broken crap, but this is
> just not how it works.

Hi Thomas,

I think we are trying persuade you like mentioned here:

> http://lkml.kernel.org/r/alpine.DEB.2.21.1807122153170.1597@xxxxxxxxxxxxxxxxxxxxxxx

But, we're not being very persuasive because we kinda forgot about the
"if and only if" condition that you mentioned.