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Re: MIPS checksum bug

To: u1@terran.org
Subject: Re: MIPS checksum bug
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Fri, 19 Sep 2008 01:17:04 +0900 (JST)
Cc: macro@linux-mips.org, linux-mips@linux-mips.org
In-reply-to: <BD7F24AB-4B0C-4FA4-ADB3-5A86E7A4624F@terran.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <Pine.LNX.4.55.0809171104290.17103@cliff.in.clinika.pl> <20080917.222350.41199051.anemo@mba.ocn.ne.jp> <BD7F24AB-4B0C-4FA4-ADB3-5A86E7A4624F@terran.org>
Sender: linux-mips-bounce@linux-mips.org
On Wed, 17 Sep 2008 15:52:45 -0700, Bryan Phillippe <u1@terran.org> wrote:
> I tested the simplified patch below (ADDC32), and it does not address  
> the checksum bug.  I suspect the problem is that we're still leaving  
> the carry bit in the upper 16 bits of the 32 bit csum returned, and  
> this is resulting in a computed checksum that is 1 greater than it  
> should be.  The upper 16 bits of the return value of this function  
> must be 0, right?

Thank you for testing.  Though this patch did not fixed your problem,
I still have a doubt on 64-bit optimization.

If your hardware could run 32-bit kernel, could you confirm the
problem can happens in 32-bit too or not?

---
Atsushi Nemoto

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