Re: discriminate single bit error hardware failure from slab corruption.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Dave Jones wrote:

On Fri, Feb 03, 2006 at 02:44:52AM +0200, Avi Kivity wrote:

>         total += hweight8(data[offset+i] ^ POISON_FREE);
> > > printk(" %02x", (unsigned char)data[offset + i]);
> >	}
> >	printk("\n");
> >@@ -1019,6 +1023,18 @@ static void dump_line(char *data, int of
> >		}
> >	}
> >	printk("\n");
> >+	switch (total) {
> >+		case 0x36:
> >+		case 0x6a:
> >+		case 0x6f:
> >+		case 0x81:
> >+		case 0xac:
> >+		case 0xd3:
> >+		case 0xd5:
> >+		case 0xea:
> >+ printk (KERN_ERR "Single bit error detected. > >Possibly bad RAM. Please run memtest86.\n");
> >+			return;
> >+	}
> > > >
> and a
> > if (total == 1)
>           printk(...);
> > here? it seems more readable and more correct as well.

More readable ? Are you kidding ?
What I wrote is smack-you-in-the-face-obvious what it's doing.
With your variant, I have to sit down and think it through.
Looks like we have mirror image brains :) - I had to scratch my scalp to figure out where all the magic numbers in the switch came from.
Perhaps well named variables will help:

   unsigned char modified_bits = data[offset+i] ^ POSION_FREE;
   int modified_bits_count = hweight8(modified_bits);
   total += modified_bits_count;

wrt correctness, what do you see wrong with my approach?
Your code will generate a false positive 8 times in 256 runs, or 1 in 32. A 3% false positive rate seems excessive, It's also sensitive to changes to POISON_FREE.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux