On 24.07.2023 11:48, Simon Gaiser wrote: > Jan Beulich: >> On 18.07.2023 23:51, Simon Gaiser wrote: >>> Roger Pau Monné: >>>> On Tue, Jul 18, 2023 at 02:26:03PM +0200, Simon Gaiser wrote: >>>>> As far as I understand the HPET legacy mode is not required on systems >>>>> with ARAT after the timer IRQ test. >>>> >>>> What's the relation with ARAT here? >>>> >>>> It would seem to me that keeping legacy replacement enabled should >>>> only be done when opt_hpet_legacy_replacement > 0, and the currently >>>> modified block is already in a opt_hpet_legacy_replacement < 0 gated >>>> chunk. >>> >>> I was concerned that on systems without ARAT cpuidle might rely on HPET >>> legacy mode being available. See _disable_pit_irq and lapic_timer_init. >>> But now that I stared at this again, I think that condition isn't >>> actually needed. If we reach that code we know that we have no working >>> PIT, but HPET is working. So _disable_pit_irq which is run after >>> check_timer (__start_xen first calls check_timer via smp_prepare_cpus >>> and only later disable_pit_irq via do_initcalls) will setup HPET >>> broadcast, which should succeed since HPET worked previously. >>> >>> So I guess we can just drop the condition (please double check, that >>> code is quite tangled and I'm not familiar with it). >> >> What you want to respect instead though is opt_hpet_legacy_replacement. > > Can you please explain what behavior you expect? As Roger pointed out > this code only runs with opt_hpet_legacy_replacement < 0 so the user > didn't make an explicit choice.
Oh, I'm sorry. Please disregard my comment then. Jan
