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

[Reinette Chatre <reinette.chatre@intel.com>]

Hi Fenghua,

On 8/9/26 7:55 PM, Fenghua Yu wrote:
> On 8/3/26 22:26, Reinette Chatre wrote:
> With minor MPAM changes, I can do simple tests on MPAM:
> -               INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emulated_by);
> +               INIT_LIST_HEAD(&mpam_ctrl->r_ctrl.emulated_by);
> 
> -               INIT_LIST_HEAD(&hw_ctrl->r_ctrl.emulated_by);
> +               INIT_LIST_HEAD(&mpam_ctrl->r_ctrl.emulated_by);
> 
> There is a branch resctrl/controls_rfc_v2.1. Seems no diff from controls_rfc_v2. Is either branch OK for base code?

hmmm ... branch resctrl/controls_rfc_v2.1 should have the change you note above
and would be the right branch for you to use.
That is the only difference with resctrl/controls_rfc_v2.

> 
>  * @emulated_by:List of controls that emulate this control. When set the containing
>  *              struct resctrl_ctrl is likely a legacy control and @emulated_by
>  *              are the finer grained hardware controls used to back the legacy
>  *              control. This emulation is hidden from user in schemata file when
>  *              rdt_resource::ctrl_mode is RESCTRL_CTRL_MODE_LEGACY and
>  *              exposed when rdt_resource::ctrl_mode is
>  *              RESCTRL_CTRL_MODE_NATIVE.
>  */
> struct resctrl_ctrl {
> ...
>         struct list_head        emulated_by;
> };
> 
> Does this mean a legacy resctrl control can be emulated by a few
> resctrl controls (which is stored in the list)?
> 
> e.g. legacy MB control can be emulated by a few controls? I thought
> "MB:" line is emulated by only one native control. e.g. "MB:" line
> is emulated by "MB_NODE:" line.

As Chenyu highlighted this is to support region-aware. 

While I did originally suggest MB_NODE to emulate MB I learned from Ben just
how troublesome this can be. I am still trying to untangle how MPAM MSC and
AMD GLBE can be supported in this new interface. Could you please consider the
most recent message on this topic:
https://lore.kernel.org/lkml/bccb1249-e722-451a-9c75-8aa846713045@intel.com/

You can find more context in thread starting at
https://lore.kernel.org/lkml/4ef15dde-2fbb-4763-93b6-4333b02d6859@arm.com/

Thank you very much.

Reinette