[fedora-arm] Broken sha512sum in coreutils

[Gordan Bobic]

Andy Green wrote:
> On 01/07/11 16:52, Somebody in the thread at some point said:
> 
>>>> I wrote about the alignment issue here on ARM:
>>>>
>>>> http://warmcat.com/_wp/2007/05/25/the-alignment-monster/
>>>
>>> Aha, I know what you are talking about now, and I am aware of such
>>> issues. Here is a similar article a friend of mine wrote:
>>>
>>> http://www.altechnative.net/?p=48
> 
> No, it's not the same issue.
> 
> On x86 as described on your link, it's just a performance penalty if 
> your members are not aligned.  On ARM without fixup, you read actual 
> garbage as described on my article.

Yup, I was more referring to the data not aligning when unioning 
structures with an array, for example. But yes, I totally get what your 
article is saying.

>> Does changing the /proc/cpu/alignment setting from 0 (ignored) to 2
>> (fixup) come with a noticeable performance penalty?
> 
> Yeah it is expensive.  Something else is up, probably with your kernel, 
> that you have so many userland alignment faults at all.
> 
> As you saw, I don't have any.

What kernel are you using? As you may have inferred, I use 2.6.36.2 with 
the vserver patches. Do you know what configuration options on the 
kernel could be causing problems like this? Optimize for size, perhaps?

And these alignment error counters (I'm assuming that is what those 
large numbers in /proc/cpu/alignment are) - do they implicitly mean 
actual calculation errors? Or are they generally harmless? I ask because 
I haven't actually had anything crash (apart from the dietlibc related 
stuff. But since the box had spent most of yesterday compiling and 
testing dietlibc, it is plausible that a lot of the counts came from 
then. I'll keep an eye on it and see if I can find what causes it.

Gordan