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by booting a CPU, we reduce the delay time

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=> works only on modern CPUs
This commit is contained in:
Stefan Lankes 2016-09-25 23:49:50 +02:00
parent 8caa6183be
commit aa84b77421
1 changed files with 44 additions and 8 deletions
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52
hermit/arch/x86/kernel/apic.c
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@ -79,6 +79,18 @@ static uint8_t irq_redirect[16] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xA, 0xB, 0xC,
static uint8_t apic_initialized = 0;
static uint8_t online[MAX_APIC_CORES] = {[0 ... MAX_APIC_CORES-1] = 0};
/*
* The Multiprocessor Specification 1.4 (1997) suggests a 10ms delay
* between the BSP asserting INIT and de-asserting INIT, when starting
* a processor. But that slows the boot time off modern processors,
* which include many cores and don't require that delay.
*
* => we use per default a lower delay to improve the boot time
* => by setting traditional_delay to 1, we switch back to the old
* way
*/
static uint8_t traditional_delay = 0;
spinlock_t bootlock = SPINLOCK_INIT;
// forward declaration
@ -459,16 +471,28 @@ static int wakeup_ap(uint32_t start_eip, uint32_t id)
uint64_t dest = ((uint64_t)id << 32);
wrmsr(0x800 + (APIC_ICR1 >> 4), dest|APIC_INT_LEVELTRIG|APIC_INT_ASSERT|APIC_DM_INIT);
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
// reset INIT
wrmsr(0x800 + (APIC_ICR1 >> 4), APIC_INT_LEVELTRIG|APIC_DM_INIT);
udelay(10000);
if (traditional_delay)
udelay(10000);
else
udelay(10);
// send out the startup
wrmsr(0x800 + (APIC_ICR1 >> 4), dest|APIC_DM_STARTUP|(start_eip >> 12));
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
// do it again
wrmsr(0x800 + (APIC_ICR1 >> 4), dest|APIC_DM_STARTUP|(start_eip >> 12));
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
//kputs("IPI done...\n");
@ -476,18 +500,30 @@ static int wakeup_ap(uint32_t start_eip, uint32_t id)
} else {
set_ipi_dest(id);
lapic_write(APIC_ICR1, APIC_INT_LEVELTRIG|APIC_INT_ASSERT|APIC_DM_INIT);
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
// reset INIT
lapic_write(APIC_ICR1, APIC_INT_LEVELTRIG|APIC_DM_INIT);
udelay(10000);
if (traditional_delay)
udelay(10000);
else
udelay(10);
// send out the startup
set_ipi_dest(id);
lapic_write(APIC_ICR1, APIC_DM_STARTUP|(start_eip >> 12));
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
// do it again
set_ipi_dest(id);
lapic_write(APIC_ICR1, APIC_DM_STARTUP|(start_eip >> 12));
udelay(200);
if (traditional_delay)
udelay(200);
else
udelay(10);
//kputs("IPI done...\n");