Messages in this thread | | | Date | Fri, 03 Feb 2006 04:05:23 +0200 | From | Avi Kivity <> | Subject | Re: discriminate single bit error hardware failure from slab corruption. |
| |
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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |