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APIC disabled if CPU lacks TSC

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- we cannot calibrate local APIC timer in such a case

- fixes possible uninitialized variable problem during calibration if no TSC
This commit is contained in:
Tomas Hruby 2010-01-13 18:22:41 +00:00
parent cc86693102
commit 42c13951a7
1 changed files with 8 additions and 7 deletions
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15
kernel/arch/i386/apic.c
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@ -155,9 +155,7 @@ PRIVATE int calib_clk_handler(irq_hook_t * hook)
u64_t tsc;
probe_ticks++;
if (cpu_has_tsc) {
read_tsc_64(&tsc);
}
read_tsc_64(&tsc);
tcrt = lapic_read(LAPIC_TIMER_CCR);
@ -385,6 +383,13 @@ PUBLIC int lapic_enable(void)
if (!lapic_addr)
return 0;
cpu_has_tsc = _cpufeature(_CPUF_I386_TSC);
if (!cpu_has_tsc) {
kprintf("CPU lacks timestamp counter, "
"cannot calibrate LAPIC timer\n");
return 0;
}
if (!lapic_enable_in_msr())
return 0;
@ -439,10 +444,6 @@ PUBLIC int lapic_enable(void)
lapic_read (LAPIC_SIVR);
*((u32_t *)lapic_eoi_addr) = 0;
cpu_has_tsc = _cpufeature(_CPUF_I386_TSC);
BOOT_VERBOSE(if (cpu_has_tsc) kprintf("CPU has Timestamp counter\n"));
apic_calibrate_clocks();
BOOT_VERBOSE(kprintf("APIC timer calibrated\n"));