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Re: How to request an IRQ for NMI on MIPS Processor

To: "Liu Hongming (Alan)" <alanliu@trident.com.cn>
Subject: Re: How to request an IRQ for NMI on MIPS Processor
From: Ralf Baechle <ralf@linux-mips.org>
Date: Tue, 11 Nov 2003 06:45:29 +0100
Cc: Adeel Malik <AdeelM@quartics.com>, linux-mips@linux-mips.org
In-reply-to: <15F9E1AE3207D6119CEA00D0B7DD5F6801C9949F@TMTMS>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <15F9E1AE3207D6119CEA00D0B7DD5F6801C9949F@TMTMS>
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On Tue, Nov 11, 2003 at 01:26:53PM +0800, Liu Hongming (Alan) wrote:

> I have understood your situation.
>  
> Under this situation,I think you need not use request_irq.

Request_irq is just the software interface; it could be used to drive
any kind of interrupt mechanism, even NMI or the two MIPS software
interrupts.  The actual problem here is the underlying hardware
mechanism and firmware.

> Just keep your 'interrupt' handler in BIOS or bootloader,
> of course,it is different with Rest Exception,since 
> many registers' status are not the same as hardware-reseting.
> You could detect the difference.Right?

Note the firmware is usually in some kind of PROM (sloooow) and also
running uncached.  One reasons of many why the MIPS NMI is only a good
idea for fatal events.

  Ralf

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