Re: [BUG] IO-APIC + timer doesn't work!

From: Jeff Mahoney
Date: Sat Apr 18 2009 - 16:47:15 EST


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Jan Kiszka wrote:
> Jeff Mahoney wrote:
>> Hi all -
>>
>> I saw this while booting 2.6.30-rc1, -rc2, and today's git, on one of
>> my development nodes. This output is with apic=debug. With noapic,
>> it still hung. Both outputs follow.
>>
>> git bisect leads to commit 8d6f0c8214928f7c5083dd54ecb69c5d615b516e,
>> but I'm not seeing anything obvious there. Backing just that change
>> out doesn't fix it.

[snip]

> Hmmmmm. That somehow reminds me of what I thought I had to fix in the
> HPET emulation of QEMU just recently [1] - because of 2.6.30-rc's behavior.
>
> Could you try if writing 'delta' a second time makes any difference on
> that box?
>
> diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
> index 648b3a2..523d72b 100644
> --- a/arch/x86/kernel/hpet.c
> +++ b/arch/x86/kernel/hpet.c
> @@ -324,6 +324,7 @@ static void hpet_set_mode(enum clock_event_mode mode,
> HPET_TN_SETVAL | HPET_TN_32BIT;
> hpet_writel(cfg, HPET_Tn_CFG(timer));
> hpet_writel((unsigned long) delta, HPET_Tn_CMP(timer));
> + hpet_writel((unsigned long) delta, HPET_Tn_CMP(timer));
> hpet_start_counter();
> hpet_print_config();
> break;
>

Thanks, Jan.

That fixed it for me.

- -Jeff

- --
Jeff Mahoney
SUSE Labs
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