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SubjectRe: [PATCH 1/5] Skip timer works.patch
Andrew Morton wrote:
> On Thu, 19 Oct 2006 17:09:22 -0700
> Zachary Amsden <zach@vmware.com> wrote:
>
>
>> Add a way to disable the timer IRQ routing check via a boot option. The
>> VMI timer code uses this to avoid triggering the pester Mingo code, which
>> probes for some very unusual and broken motherboard routings. It fires
>> 100% of the time when using a paravirtual delay mechanism instead of
>> using a realtime delay, since there is no elapsed real time, and the 4 timer
>> IRQs have not yet been delivered.
>>
>> In addition, it is entirely possible, though improbable, that this bug
>> could surface on real hardware which picks a particularly bad time to enter
>> SMM mode, causing a long latency during one of the timer IRQs.
>>
>> While here, make check_timer be __init.
>>
>>
>
> Andi seems to have merged this patch but from somewhere I picked up a
> different version, below.
>
> I think the version I have is better. Because the patch Andi has merged is
> cast in terms of "irq testing", which is broad. But that's not what the
> patch does - the patch handles only timers.
>
> IOW, this:
>
>
>> +
>> + noirqtest [IA-32,APIC] Disables the code which tests for broken
>> + timer IRQ sources.
>>
>
> is misleadingly named. This:
>
> + no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
> + broken timer IRQ sources.
> +
>
> is better, no?
>
> But right now, I'll settle for anything which usually compiles.
>
>

Yes, the name sucks. There is no real reason to actually have a boot
parameter at all once the paravirt / VMI patches are in, but I wanted
something to be able to set timer_irq_really_works until then to avoid
someone accidentally removing it.

Zach
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