Messages in this thread | | | Date | Thu, 6 Apr 2017 10:43:01 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RFC PATCH 0/6] Unify the Interrupt Mode and setup it as soon as possible |
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On Wed, 29 Mar 2017, Dou Liyang wrote: > The purpose of this patchset is Unifing these setup steps and executing as > soon as possible as follows: > > start_kernel > ---------------+ > | > | > | > | init_IRQ > +---->---+----+ > | | > | | +--------------------+ > | +----> | 4. init_bsp_APIC | > | +--------------------+ > v > > By the way, Also fix a bug about kexec[3]. > > > Some doubts, need help: > > 1. Patchset has influence on IOMMU in enable_IR_x2apic(). Not sure > it can be in advance?
That should work.
> 2. Due to > > Commit 8c3ba8d04924 ("x86, apic: ack all pending irqs when crashed/on kexec") > > ..., patchset also needs TSC and uses the "cpu_khz" in setup_local_APIC(). > And a warning[4] will be triggered when crashed/on kexec. Not sure how to > modify?
The local APIC timer initialization cannot be run from init_IRQ().
The problem here is that CPU and TSC frequency calibration depends on the PIT/HPET interrupt (irq 0) working for machines which cannot calibrate via MSR/CPUID or if fast calibration via PIT fails.
So we need to split that initialization into several parts:
1) Set up the APIC/IOAPIC (including testing whether the timer interrupt works)
2) Calibrate TSC
3) Set up the local APIC timer
Thanks,
tglx
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