Re: [PATCH 1/5] Skip timer works.patch

[Zachary Amsden]

Andrew Morton wrote:
> On Thu, 19 Oct 2006 17:09:22 -0700
> Zachary Amsden <zach@xxxxxxxxxx> 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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