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

["Chen, Yu C" <yu.c.chen@intel.com>]

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.

thanks,
Chenyu