Re: [PATCH 5/5] sched_ext: Gate scx_bpf_cidperf_set() behind a new SCX_CAP_PERF

On Fri, Jul 24, 2026 at 06:46:05PM +0000, [email protected] wrote:
> [Severity: High]
> Does unconditionally passing SCX_CAP_PERF break backward compatibility on
> older kernels?
>
> If scx_qmap is loaded on a pre-gate kernel where SCX_CAP_PERF is not part of
> __SCX_CAP_ALL, won't the kernel's scx_bpf_sub_grant() and scx_bpf_sub_revoke()
> reject the unknown cap bit?

It would, but that's fine. The sub-scheduler caps interface is still
going through initial development and there is no cross-version
compatibility commitment for it yet. The in-tree schedulers track the
in-tree kernel for these interfaces.

Thanks.

--
tejun