RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-31 07:48:11 +00:00
Code Issues Activity Actions

Kernel: Fix HPET timer not firing in Bochs

Browse source 
* Change the register structures to use the volatile keyword explicitly
  on the register values. This avoids accidentally omitting it as any
  access will be guaranteed volatile.
* Don't assume we can read/write 64 bit value to the main counter and
  the comparator. Not all HPET implementations may support this. So,
  just use 32 bit words to access the registers. This ultimately works
  around a bug in Bochs 2.6.11 that loses 32 bits of a 64 bit write to
  a timer's comparator register (it internally writes one half and
  clears the Tn_VAL_SET_CNF bit, and then because it's cleared it
  fails to write the second half).
* Properly calculate the tick duration in calculate_ticks_in_nanoseconds
* As per specification, changing the frequency of one periodic timer
  requires a restart of all periodic timers as it requires the main
  counter to be reset.
This commit is contained in:
Tom 2020-11-03 13:19:42 -07:00 • committed by Andreas Kling
parent 348cd0fdc1
commit d5bb5d109b
4 changed files with 158 additions and 95 deletions
Download patch file Download diff file Expand all files Collapse all files

3
Kernel/Time/TimeManagement.cpp
View file

@ -225,9 +225,10 @@ bool TimeManagement::probe_and_set_non_legacy_hardware_timers()
}
m_system_timer->set_callback(Scheduler::timer_tick);
m_time_keeper_timer->set_callback(TimeManagement::update_time);
dbg() << "Reset timers";
m_system_timer->try_to_set_frequency(m_system_timer->calculate_nearest_possible_frequency(1024));
m_time_keeper_timer->set_callback(TimeManagement::update_time);
m_time_keeper_timer->try_to_set_frequency(OPTIMAL_TICKS_PER_SECOND_RATE);
return true;