Kernel: Fix APIC timer frequency

The APIC current count register decrements on each clock tick. Fixes the APIC timer firing much less frequently than it should be.
jlechem · Oct 29, 2020 · d076b00 · d076b00
1 parent 3fa0b88
commit d076b00
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/Kernel/Time/APICTimer.cpp b/Kernel/Time/APICTimer.cpp
@@ -112,7 +112,7 @@ bool APICTimer::calibrate(HardwareTimerBase& calibration_source)
 
  disable_local_timer();
 
- auto delta_apic_count = end_apic_count - start_apic_count;
+ auto delta_apic_count = start_apic_count - end_apic_count; // The APIC current count register decrements!
  m_timer_period = (delta_apic_count * apic.get_timer_divisor()) / ticks_in_100ms;
 
  auto apic_freq = (delta_apic_count * apic.get_timer_divisor()) / apic.get_timer_divisor();