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Re: [kdb] KDB makes Nehalem hang at early boot until key press

To: Thomas Renninger <trenn@xxxxxxx>
Subject: Re: [kdb] KDB makes Nehalem hang at early boot until key press
From: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
Date: Fri, 30 Oct 2009 08:36:31 -0500
Cc: kdb@xxxxxxxxxxx
In-reply-to: <200910301102.57634.trenn@xxxxxxx>
References: <200910301102.57634.trenn@xxxxxxx>
User-agent: Thunderbird 2.0.0.23 (X11/20090817)
Thomas Renninger wrote:
> Hi,
>
> we currently have a problem with latest Intel CPUs/BIOSes:
> If the machine gets booted it hangs in:
> init/main.c:
> kdb_init();
>
> As soon as an irq via keyboard is triggered, the machine continues 
> booting and everything is fine.
>
> Is this known already? Can someone point me to a patch?
>
> If not, is there a repo having the latest code, I could try
> out whether the latest version works.
>
> IMO something like the attached patch makes sense?
> This fixes the problem with kdb=off (our default).
> But I am anxious that kdb code could still get activitated somehow
> and the machine might oops when trying to access not initialized
> kdb structures? Could someone give an estimation how risky that
> patch really is?
>
> Still the real bug should be found and if this is not known, can someone 
> give me a pointer to what this problem could be related and where I 
> should look closer at, please.
>   

In the version of kdb which attached to kgdb, I wonder if you see the
same sort of behavior?

I am not sure which kernel base you need, but kdb prototype attached to
kgdb exists for the 2.6.31 and 2.6.32 kernel.

The code you patched does not exist in the kdb+kgdb code base.

Jason.

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