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Re: [PATCH] Proposed NMI handling interface...

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] Proposed NMI handling interface...
From: Thomas Horsten <thomas@horsten.com>
Date: Thu, 9 Oct 2003 13:55:12 +0100 (BST)
Cc: "Steven J. Hill" <sjhill@realitydiluted.com>, <linux-mips@linux-mips.org>
In-reply-to: <20031008160600.GA19102@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
On Wed, 8 Oct 2003, Ralf Baechle wrote:

> That hook you're proposing isn't even necessary in generic code.  NMI
> on MIPS hardware is a fairly odd type of exception - it goes straight to
> 0xbfc00000 which usually is a a firmware address - and lots of firmware
> doesn't even offer an NMI hook.  So for those cases where it's possible,
> you need to do something firmware anyway before jumping to Linux's NMI
> handler.  An additional problem with the NMI design of MIPS is it's using
> ErrorEPC, just like cache errors so you better pray - or simply design
> systems only to rely on NMI for debugging and catastrophic failures.

On Lasat boards NMI is used to reboot into Service Mode. There's no hook
to override this behaviour.

// Thomas


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