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

["Moger, Babu" <bmoger@amd.com>]

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