On Tue, Nov 17, 2020 at 10:00:18PM +0100, Mathieu Chouquet-Stringer wrote: > I'm late to the party but it seems allowing MSR_IA32_ENERGY_PERF_BIAS > has the downside of flagging the kernel as tainted without telling you > why if you use something like x86_energy_perf_policy (from > tools/power/x86/x86_energy_perf_policy) which itself is used by tuned.
Not for long: https://git.kernel.org/tip/fe0a5788624c8b8f113a35bbe4636e37f9321241 > So while both documentation and tools should be updated as to be clearer > and to not taint the kernel respectively, there's something that remains > to be done to explain why or how the kernel got tainted because of > poking into MSRs... Because if you poke at random MSRs and you manage to "configure" your CPU to run "out of spec" - this is what the taint flag is called: TAINT_CPU_OUT_OF_SPEC - then this is exactly the case you've created: a CPU executing outside of specifications. I agree with the update-the-documentation aspect - S does not mean only SMP kernel on !SMP-capable CPU but the more general, CPU is out of spec. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
