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Kernel: Fix APIC timer calibration to be more accurate

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We were calibrating it to 260 instead of 250 ticks per second (being
off by one for the 1/10th second calibration time), resulting in
ticks of only ~3.6 ms instead of ~4ms. This gets us closer to ~4ms,
but because the APIC isn't nearly as precise as e.g. HPET, it will
only be a best effort. Then, use the higher precision reference
timer to more accurately calculate how many ticks we actually get
each second.

Also the frequency calculation was off, causing a "Frequency too slow"
error with VMware.

Fixes some problems observed in #5539
This commit is contained in:
Tom 2021-02-28 11:47:03 -07:00 • committed by Andreas Kling
parent f66adbdd95
commit cdbd878a14
7 changed files with 64 additions and 23 deletions
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5
Kernel/Time/HPET.h
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@ -46,6 +46,8 @@ public:
static HPET& the();
u64 frequency() const { return m_frequency; }
u64 raw_counter_ticks_to_ns(u64) const;
u64 ns_to_raw_counter_ticks(u64) const;
const NonnullRefPtrVector<HPETComparator>& comparators() const { return m_comparators; }
void disable(const HPETComparator&);
@ -60,6 +62,7 @@ public:
void disable_periodic_interrupt(const HPETComparator& comparator);
u64 update_time(u64& seconds_since_boot, u32& ticks_this_second, bool query_only);
u64 read_main_counter_unsafe() const;
u64 read_main_counter() const;
Vector<unsigned> capable_interrupt_numbers(u8 comparator_number);
@ -75,7 +78,7 @@ private:
bool is_periodic_capable(u8 comparator_number);
void set_comparators_to_optimal_interrupt_state(size_t timers_count);
u64 calculate_ticks_in_nanoseconds() const;
u64 nanoseconds_to_raw_ticks() const;
PhysicalAddress find_acpi_hpet_registers_block();
explicit HPET(PhysicalAddress acpi_hpet);