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Subject[patch] clockevents: drivers for i386, fix #2

* Ingo Molnar <mingo@elte.hu> wrote:

> yeah, i suspect it works again if you disable:
>
> CONFIG_X86_UP_APIC=y
> CONFIG_X86_UP_IOAPIC=y
> CONFIG_X86_LOCAL_APIC=y
> CONFIG_X86_IO_APIC=y
>
> as the slowdown has the feeling of a runaway lapic timer irq.
>
> from code review so far we can only see an udelay(10) difference in
> the initialization sequence of the PIT - we'll send a fix for that but
> i dont think that's the cause of the bug.

the patch below fixes that particular bug. But ... the symptoms you are
describing have the feeling of being apic related.

Ingo

-------------------->
Subject: clockevents: drivers for i386, fix #2
From: Ingo Molnar <mingo@elte.hu>
add back a mistakenly removed udelay(10) to the PIT initialization
sequence.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/i386/kernel/i8253.c | 1 +
1 file changed, 1 insertion(+)
Index: linux/arch/i386/kernel/i8253.c
===================================================================
--- linux.orig/arch/i386/kernel/i8253.c
+++ linux/arch/i386/kernel/i8253.c
@@ -45,6 +45,7 @@ static void init_pit_timer(enum clock_ev
outb_p(0x34, PIT_MODE);
udelay(10);
outb_p(LATCH & 0xff , PIT_CH0); /* LSB */
+ udelay(10);
outb(LATCH >> 8 , PIT_CH0); /* MSB */
break;

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