# Broken chipset / Reroute for broken IRQs

## aCOSwt

Hello,

Trying to find my way in the configuration of a "low-latency" kernel, I found the X86_REROUTE_FOR_BROKEN_IRQS option flag activated by default. (in the Processor & Features section)

Taking into account that :

- the associated feature increases the latency I am trying to limit,

- this feature is needed only with specific "broken" chipsets,

I do not wish to set it if my hardware does not require it.

=> Where can I find a list of such "broken" chipsets in order to check mine against this list ?

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## turtles

I think that broken IRQ have to do with the bios and mother board design more than a specific chip.

You could disable the option and check the output of

```
 dmesg
```

 fo irq related errors and non working hard ware.

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## aCOSwt

 *turtles wrote:*   

> I think that broken IRQ have to do with the bios and mother board design more than a specific chip.

 

It had to do with the motherboard design including a specific Intel chip : The 825x APIC.

Modern design still include this "broken" chip but as part of the northbridge.

=> Broken IRQs have no longer to do with mobo's design but with the design of the northbridge.

=> Broken IRQ's still occuring in such an architecture imply a "broken" chipset.

I have built my kernel while playing with the LiveDVD 10.1 for which X86_REROUTE_FOR_BROKEN_IRQ appears not set when I zcat /proc/config.gz

And approximatly everything works apparently well.

From this, crossing my fingers, I infere that, for the time being, my Intel P43 is not "broken"   :Cool: 

Anyway ! Thank you for answering turtles.

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