On Tue, Dec 19, 2017 at 04:23:07PM +0100, Peter Zijlstra wrote: > On Tue, Dec 19, 2017 at 06:48:24PM +0800, Zhang Rui wrote: > > On Mon, 2017-12-18 at 21:28 +0100, Peter Zijlstra wrote: > > > Hi, can you see if this makes you Surface boot? > > > > > No, it does not boot. > > So I'm confused on the lapic calibration. > > That stuff uses global_clock_event, which is initially the i8253 (PIT), > but because !PIC this thing won't be there either on your platform. > > Then we initialize I/O APIC, and your machine has: > > [ 0.000000] IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-119 > [ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl) > [ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level) > [ 0.000000] ACPI: IRQ0 used by override. > [ 0.000000] ACPI: IRQ9 used by override. > > So your ACPI table has an override for IRQ2 and routes it to IRQ0. > > Then we initialize HPET, and we _always_ do hpet_enable_legacy_int(), > which sets the LegacyRouting bit. 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 > Timer 1 will be routed to IRQ8 in Non-APIC or IRQ8 in the I/O APIC > Timer 2-n will be routed as per the routing in the timer n config > registers. > > If the LegacyReplacement Route bit is set, the individual routing bits > for timers 0 and 1 (APIC or FSB) will have no impact. > > And then we set global_clock_event to &hpet_clockevent. > > At this point that _SHOULD_ work afaict, even without actual PIC > present. > > Sometime after that we call into calibrate_APIC_clock() -- because > !TSC_DEADLINE -- and this is where you get stuck, because > global_clock_event is not in fact delivering interrupts. > > Thomas may have more clue, we'll have to wait for him to have a > time-slot available.
What does your /proc/interrupts look like (on a tsc-deadline boot) ? 0: is the HPET, LOC: is the lapic/tsc-deadline On my SKL desktop I get 21 PIT/HPET ticks on CPU0 before lapic takes over.
