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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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2
Kernel/Random.cpp
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@ -71,7 +71,7 @@ UNMAP_AFTER_INIT KernelRng::KernelRng()
klog() << "KernelRng: Using HPET as entropy source";
for (size_t i = 0; i < resource().pool_count * resource().reseed_threshold; ++i) {
u64 hpet_time = HPET::the().read_main_counter();
u64 hpet_time = HPET::the().read_main_counter_unsafe();
this->resource().add_random_event(hpet_time, i % 32);
}
} else {