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

[Chen Yu <chen.yu@linux.dev>]

On Tue, Aug 11, 2026 at 11:49:12AM +0800, Chen, Yu C wrote:
> > I find "region-aware controllers at the same level as legacy controller" together with
> > "per controller enable/disable" conflicting since it creates impression that user space can
> > enable/disable the controllers independently while there is a required dependency among the
> > different controllers based on whether hardware has region-aware MBA enabled or not. Even
> > here there would be a requirement to communicate to userspace which controllers could be
> > enabled/disabled together ... which is the same as the emulated list, no?
> 
> I see. So we actually need a single option (control_mode) to switch between
> modes (legacy vs.
> native, mutually exclusive), rather than giving each controller its own
> independent enable/disable
> toggle. The emulated list is one way to implement control_mode, ensuring
> "legacy" and "native"
> are mutually exclusive.
>

While adjusting the region aware code on this emulation part, a minor issue is found
in commit ("fs/resctrl: Support emulated controls")

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index cac4b3293cef..ab7d3fa3f337 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -124,7 +124,7 @@ void rdt_staged_configs_clear(void)
                        if (list_empty(&ctrl->emulated_by))
                                continue;
                        list_for_each_entry(em_ctrl, &ctrl->emulated_by, entry) {
-                               list_for_each_entry_rcu(dom, &ctrl->domains, hdr.list, lockdep_is_cpus_held())
+                               list_for_each_entry_rcu(dom, &em_ctrl->domains, hdr.list, lockdep_is_cpus_held())
                                        memset(dom->staged_config, 0, sizeof(dom->staged_config));
                        }
                }
 
thanks,
Chenyu