linux-kernel - Re: single bit flip detector.

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Date:	Tue, 1 Aug 2006 18:30:11 -0400
From:	Dave Jones <davej@...hat.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: single bit flip detector.

On Tue, Aug 01, 2006 at 11:14:27PM +0100, Alan Cox wrote:
 > Ar Maw, 2006-08-01 am 14:44 -0400, ysgrifennodd Dave Jones:
 > > +		case POISON_FREE ^ 0x01:
 > > +		case POISON_FREE ^ 0x02:
 > > +		case POISON_FREE ^ 0x04:
 > > +		case POISON_FREE ^ 0x08:
 > > +		case POISON_FREE ^ 0x10:
 > > +		case POISON_FREE ^ 0x20:
 > > +		case POISON_FREE ^ 0x40:
 > > +		case POISON_FREE ^ 0x80:
 > > +			printk (KERN_ERR "Single bit error detected. Possibly bad RAM.\n");
 > > +#ifdef CONFIG_X86
 > > +			printk (KERN_ERR "Run memtest86 or other memory test tool.\n");
 > > +#endif
 > > +			return;
 > 
 > Gack .. NAK
 > 
 > #1: Do we want memtest86 or memtest86+ ?

I doubt it really matters.

 > #2: The check is horrible and there is an elegant implementation for
 > single bit.
 > 
 > 	errors = value ^ expected;
 > 	if (errors && !(errors & (errors - 1)))
 > 		printk(KERN_ERR "Single bit error detected....");
 
Good call, I'll hack that up.

		Dave

-- 
http://www.codemonkey.org.uk
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