Re: [RFC v2] arm,x86,fs/resctrl: Generic schema description Proof of Concept

[Moger, Babu]

Hi Chenyu,

On 8/7/2026 10:35 AM, Chen, Yu C wrote:
> Hi Babu,
>
> On 8/7/2026 10:14 PM, Moger, Babu wrote:
>
> [ ... ]
>
> > > > Is same needed for x86? I don't see any initialization of the
> > > > "r_ctrl.emulated_by" lists in similar initialization functions.
> > > x86 "emulated_by" list initialization should be in both branches.
> > >
> > > Branch resctrl/controls_rfc_v2.1 combined all "emulated_by" list 
> > > initialization
> > > (for x86 and MPAM) into commit:
> > > 3407e523c988 ("fs/resctrl: Introduce emulated controls and control 
> > > mode")
> > >
> > > In the original resctrl/controls_rfc_v2 the x86 "emulated_by" list 
> > > initialization can
> > > be found in commit fbed64f80515 ("x86/resctrl: SAMPLE: Emulated 
> > > controls")
> >
> > Looking at the commit:
> >
> > commit 3407e523c988 ("fs/resctrl: Introduce emulated controls and 
> > control mode")
> >
> > Based on the patch description, emulated controls are intended to be 
> > used only when there is a difference between the native and legacy 
> > controls. If no such difference exists, both modes should operate 
> > identically.
> >
> > For MBA(AMD) and GMBA, there does not appear to be any difference 
> > between the two modes. Is that understanding correct?
>
> Yes I think so. __rdt_get_mem_config_amd() does
> INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emulated_by), so the list is
> a valid empty one and resctrl_enabled_ctrl_iter_next() short-circuits
> on list_empty() regardless of ctrl_mode, meaning MBA
> expose the same single control in either mode.

Got it,
Thank you
Babu