Re: Regression: unable to boot after commit bd9240a18edf ("x86/apic: Add TSC_DEADLINE quirk due to errata") - Surface Pro 4 SKL

[Peter Zijlstra]

On Tue, Dec 19, 2017 at 11:42:41PM +0800, Zhang Rui wrote:
> On Tue, 2017-12-19 at 16:23 +0100, Peter Zijlstra wrote:

> > [    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
> > [    0.000000] ACPI: IRQ0 used by override.
> > 
> > So your ACPI table has an override for IRQ2 and routes it to IRQ0.

^ this

> >  The HPET document says:
> > 
> >   If the ENABLE_CNF bit and the LEG_RT_CNF bit are both set, then the
> >   interrupts will be routed as follows:
> > 
> >     Timer 0 will be routed to IRQ0 in Non-APIC or IRQ2 in the I/O APIC
> 
> But AFAICS, the HPET emulated timer interrupts goes to IRQ0

Right, so see that ACPI override, that routes I/O APIC IRQ2 to IRQ0, or
it _should_.

Clearly something is messed up here.. but I've no idea what. That whole
IRQ routing stuff is confusing.