single shot timer interrupts fix

- accidentaly this wasn't part of the SMP merge and the implementation
  remained uncomplete with the timer keeping ticking periodically

- APIC timer is set for a signel shot and restarted everytime it
  expires. This way we can keep the AP's trully idle

- the timer is restarted a little later before leaving to userspace

- LAPIC_TIMER_ICR is written before LAPIC_LVTTR so the newest value is
  used
This commit is contained in:
Tomas Hruby 2010-10-21 17:07:01 +00:00
parent ebbc730fc3
commit a1eefc013e
3 changed files with 6 additions and 5 deletions

View file

@ -508,14 +508,14 @@ PUBLIC void lapic_set_timer_one_shot(const u32_t usec)
ticks_per_us = (lapic_bus_freq[cpu] / 1000000) * config_apic_timer_x;
lapic_write(LAPIC_TIMER_ICR, usec * ticks_per_us);
lvtt = APIC_TDCR_1;
lapic_write(LAPIC_TIMER_DCR, lvtt);
/* configure timer as one-shot */
lvtt = APIC_TIMER_INT_VECTOR;
lapic_write(LAPIC_LVTTR, lvtt);
lapic_write(LAPIC_TIMER_ICR, usec * ticks_per_us);
}
PUBLIC void lapic_set_timer_periodic(const unsigned freq)

View file

@ -124,8 +124,8 @@ PUBLIC int init_local_timer(unsigned freq)
/* if we know the address, lapic is enabled and we should use it */
if (lapic_addr) {
unsigned cpu = cpuid;
lapic_set_timer_periodic(freq);
tsc_per_ms[cpu] = div64u(cpu_get_freq(cpu), 1000);
lapic_set_timer_one_shot(1000000/system_hz);
} else
{
BOOT_VERBOSE(printf("Initiating legacy i8253 timer\n"));

View file

@ -370,8 +370,6 @@ check_misc_flags:
p = arch_finish_switch_to_user();
assert(!is_zero64(p->p_cpu_time_left));
restart_local_timer();
context_stop(proc_addr(KERNEL));
/* If the process isn't the owner of FPU, enable the FPU exception */
@ -389,6 +387,9 @@ check_misc_flags:
#ifdef CONFIG_SMP
refresh_tlb();
#endif
restart_local_timer();
/*
* restore_user_context() carries out the actual mode switch from kernel
* to userspace. This function does not return