Re: [PATCH v3 15/17] intel_iommu: Modify x-scalable-mode to be string option to expose scalable modern mode

[Jason Wang <jasowang@redhat.com>]

On Fri, Sep 27, 2024 at 2:39 PM Duan, Zhenzhong
<zhenzhong.duan@intel.com> wrote:
>
>
>
> >-----Original Message-----
> >From: Jason Wang <jasowang@redhat.com>
> >Subject: Re: [PATCH v3 15/17] intel_iommu: Modify x-scalable-mode to be
> >string option to expose scalable modern mode
> >
> >On Wed, Sep 11, 2024 at 1:27 PM Zhenzhong Duan
> ><zhenzhong.duan@intel.com> wrote:
> >>
> >> From: Yi Liu <yi.l.liu@intel.com>
> >>
> >> Intel VT-d 3.0 introduces scalable mode, and it has a bunch of capabilities
> >> related to scalable mode translation, thus there are multiple combinations.
> >> While this vIOMMU implementation wants to simplify it for user by
> >providing
> >> typical combinations. User could config it by "x-scalable-mode" option. The
> >> usage is as below:
> >>
> >> "-device intel-iommu,x-scalable-mode=["legacy"|"modern"|"off"]"
> >>
> >>  - "legacy": gives support for stage-2 page table
> >>  - "modern": gives support for stage-1 page table
> >>  - "off": no scalable mode support
> >>  - any other string, will throw error
> >
> >Those we had "x" prefix but I wonder if this is the best option for
> >enabling scalable-modern mode since the "on" is illegal after this
> >change.
>
> Yes, I was thinking "x" means not stable user interface yet.
> But I do agree with you it's better to keep stable user interface whenever possible.
>
> >
> >Maybe it's better to just have an "x-fls". Or if we considering the
> >scalable mode is kind of complete, it's time to get rid of "x" prefix.
>
> Ah, I thought this is a question only maintainers and reviewers can decide if it's complete.
> If no voice on that, I'd like to add "x-fls" as you suggested and keep x-scalable-mode unchanged.

A question here:

Are there any other major features that are still lacking for scalable
mode? If not, maybe we can get rid of the "x" prefix?

Thanks

>
> Thanks
> Zhenzhong
>