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

[Chen, Yu C]

Hi Ben,

On 7/2/2026 10:27 PM, Ben Horgan wrote:
> Hi Chenyu,

[ ... ]

> > The following are current thoughts on how Control B can emulate Control A.
> > May I know if this direction is acceptable?
> >
> > The main idea is that, Legacy MBA controller delegates to region-aware MBA
> > controller via a pointer, with its hw_update function converting
> > percentages
> > to the target's value range.
> >
> > struct resctrl_hw_ctrl {
> >      struct resctrl_ctrl  r_ctrl;
> >      unsigned int         msr_base;
> >      void                 (*hw_update)(struct hw_param *m);
> >      /* points to the backing controller */
> >      struct resctrl_ctrl  *r_ctrl_emul;  <-- newly added
> > };
>
> What's the reason for this being in the architecture specific code? I
> would expect that the resctrl core code would need to know about any
> emulation even if the exact emulation is architecture specific?

I was thinking that the low-level emulation was implemented by the
hardware/architecture, so I put it within resctrl_hw_ctrl. But you
are right - the generic resctrl might need to be aware of the emulation,
because the "info" directory needs to display the emulation hierarchy.
Let me have a try at moving it into the generic resctrl, like into
struct resctrl_ctrl.

thanks,
Chenyu