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The current read result is consumed by cpumod_attr_show(), but you are right that the persistent cached-value plumbing is unnecessary. For v2, I plan to return the value through call.value, emit it directly, and remove the cached fields and helpers that no longer have a consumer. I also agree about the permissions issue. The register-backed reads perform a synchronous IPI, so allowing unprivileged reads could generate a steady IPI stream. I plan to change the six register-backed controls to 0600 and retain affected_cpus as 0444 metadata. I have recorded your Tested-by, but I will confirm that it still applies after these changes before carrying it into v2. The resend is currently on hold pending arm64 maintainer direction. Thanks, Koba