Re: [RFC][PATCH 0/2] x86: Add "virt flags"

[Ingo Molnar <mingo@elte.hu>]

* Sheng Yang <sheng.yang@intel.com> wrote:

> Hi, Ingo
> 
> (sorry for former noises, I mistake the address... Report to lkml) 
> I've sent this patchset before, but got no comments from upstream at 
> that time.  So I'd like to resend this.
> 
> The virt flags is used for the important hardware virtualization 
> features, like EPT of incoming Nehalem. Because the feature 
> availability are read from MSRs, and I think virtualization features 
> should not at the same level as "vmx", so I added a new flags catagory 
> here.
> 
> But I still have concern, for this may broke some not that reliable 
> userspace programs. So Avi suggested that we can add more fields to 
> flags rather than a new catagory.  What's your opinion? We indeed need 
> a generic user visible way to tell the HW virtualization features.

hm, i think extending the already existing flags category sounds like a 
better solution than the separate virtual CPU flags line in 
/proc/cpuinfo. We already have self-invented flag entries (such as 
X86_FEATURE_NOPL), and adding more for virtualization would be quite 
natural to do, as long as it's reasonably close to the meaning of a 'CPU 
feature'.

Peter, what would be your preference?

	Ingo