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better lapic writes, suggested by cliff

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rsc 2007-09-27 19:33:46 +00:00
parent 4721271961
commit b5dcebdbeb
1 changed files with 26 additions and 19 deletions
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45
lapic.c
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@ -37,6 +37,13 @@
volatile uint *lapic; // Initialized in mp.c
static void
lapicw(int index, int value)
{
lapic[index] = value;
lapic[ID]; // wait for write to finish, by reading
}
//PAGEBREAK!
void
lapic_init(int c)
@ -45,43 +52,43 @@ lapic_init(int c)
return;
// Enable local APIC; set spurious interrupt vector.
lapic[SVR] = ENABLE | (IRQ_OFFSET+IRQ_SPURIOUS);
lapicw(SVR, ENABLE | (IRQ_OFFSET+IRQ_SPURIOUS));
// The timer repeatedly counts down at bus frequency
// from lapic[TICR] and then issues an interrupt.
// If xv6 cared more about precise timekeeping,
// TICR would be calibrated using an external time source.
lapic[TDCR] = X1;
lapic[TIMER] = PERIODIC | (IRQ_OFFSET + IRQ_TIMER);
lapic[TICR] = 10000000;
lapicw(TDCR, X1);
lapicw(TIMER, PERIODIC | (IRQ_OFFSET + IRQ_TIMER));
lapicw(TICR, 10000000);
// Disable logical interrupt lines.
lapic[LINT0] = MASKED;
lapic[LINT1] = MASKED;
lapicw(LINT0, MASKED);
lapicw(LINT1, MASKED);
// Disable performance counter overflow interrupts
// on machines that provide that interrupt entry.
if(((lapic[VER]>>16) & 0xFF) >= 4)
lapic[PCINT] = MASKED;
lapicw(PCINT, MASKED);
// Map error interrupt to IRQ_ERROR.
lapic[ERROR] = IRQ_OFFSET+IRQ_ERROR;
lapicw(ERROR, IRQ_OFFSET+IRQ_ERROR);
// Clear error status register (requires back-to-back writes).
lapic[ESR] = 0;
lapic[ESR] = 0;
lapicw(ESR, 0);
lapicw(ESR, 0);
// Ack any outstanding interrupts.
lapic[EOI] = 0;
lapicw(EOI, 0);
// Send an Init Level De-Assert to synchronise arbitration ID's.
lapic[ICRHI] = 0;
lapic[ICRLO] = BCAST | INIT | LEVEL;
lapicw(ICRHI, 0);
lapicw(ICRLO, BCAST | INIT | LEVEL);
while(lapic[ICRLO] & DELIVS)
;
// Enable interrupts on the APIC (but not on the processor).
lapic[TPR] = 0;
lapicw(TPR, 0);
}
int
@ -116,7 +123,7 @@ void
lapic_eoi(void)
{
if(lapic)
lapic[EOI] = 0;
lapicw(EOI, 0);
}
// Spin for a given number of microseconds.
@ -139,16 +146,16 @@ lapic_startap(uchar apicid, uint addr)
volatile int j = 0;
// Send INIT interrupt to reset other CPU.
lapic[ICRHI] = apicid<<24;
lapic[ICRLO] = INIT | LEVEL;
lapicw(ICRHI, apicid<<24);
lapicw(ICRLO, INIT | LEVEL);
microdelay(10);
// Send startup IPI (twice!) to enter bootstrap code.
// Regular hardware wants it twice, but Bochs complains.
// Too bad for Bochs.
for(i = 0; i < 2; i++){
lapic[ICRHI] = apicid<<24;
lapic[ICRLO] = STARTUP | (addr>>12);
lapicw(ICRHI, apicid<<24);
lapicw(ICRLO, STARTUP | (addr>>12));
for(j=0; j<10000; j++); // 200us
}
}