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Re: NR_IRQS and possible irq values on malta

To: Guy Streeter <guy.streeter@gmail.com>
Subject: Re: NR_IRQS and possible irq values on malta
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Thu, 3 Feb 2005 22:45:06 +0000 (GMT)
Cc: linux-mips <linux-mips@linux-mips.org>
In-reply-to: <52dd17640502031426660c7196@mail.gmail.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <52dd17640502031426660c7196@mail.gmail.com>
Sender: linux-mips-bounce@linux-mips.org
On Thu, 3 Feb 2005, Guy Streeter wrote:

> In mips_pcibios_iack() the irq number is obtained like this:
> 
>               irq = GT_READ(GT_PCI0_IACK_OFS);
>               irq &= 0xff;
> 
> (for coreLV, but similarly for others). This value is used to index
> into an array of size NR_IRQS, which is set in mach-generic/irq.h to
> 128.
>  I realize that when things work right, the value of irq isn't likely
> to get that big, but it seems to me it should be masked down to 127 or
> the NR_IRQS value should be larger. I have no opinion which is the
> right thing to do.

 It looks like a problem in __do_IRQ() (in kernel/irq/handle.c) -- it 
should probably call "BUG_ON(irq >= NR_IRQS)".  MIPS-specific code doesn't 
care.

  Maciej

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