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Date: Thu, 7 Dec 2000 17:13:53 +0100
From: Andi Kleen <ak@suse.de>
To: richardj_moore@uk.ibm.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: Why is double_fault serviced by a trap gate?
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In-Reply-To: <802569AE.00588787.00@d06mta06.portsmouth.uk.ibm.com>; from richardj_moore@uk.ibm.com on Thu, Dec 07, 2000 at 04:04:21PM +0000
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On Thu, Dec 07, 2000 at 04:04:21PM +0000, richardj_moore@uk.ibm.com wrote:
> 
> 
> Why is double_fault serviced by a trap gate? The problem with this is that
> any double-fault caused by a stack-fault, which is the usual reason,
> becomes a triple-fault. And a triple-fault results in a processor reset or
> shutdown making the fault damn near impossible to get any information on.
> 
> Oughtn't the double-fault exception handler be serviced by a task gate? And
> similarly the NMI handler in case the NMI is on the current stack page
> frame?

Sounds like a good idea, when you can afford a few K for a special
NMI/double fault stack. On x86-64 it is planned to do that.


-Andi
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