One more question on alignment

[subin gangadharan]

On Sat, Aug 6, 2011 at 12:37 PM, Daniel Baluta <daniel.baluta at gmail.com>wrote:

> On Sat, Aug 6, 2011 at 10:17 PM, subin gangadharan
> <subingangadharan at gmail.com> wrote:
> > Hi,
> > This is a text excerpt from the article [1].
> > Below paragraph I didn't understand quite well.Mainly in bold
> letters.Could
> > anybody please explain how this will lead to an infinite loop.
>
> It seems self-explanatory. Most atomic ops are written to retry upon a
> failed
> store, and  on PowerPC an atomic store to an unaligned address always
> fails,
> thus the processor will infinitely try to store the value, without having
> the chance to fix the unaligned access (as would have happened if an
> exception
> was thrown).
>
> >
> > Unfortunately, the PowerPC does not throw an exception when atomically
> > storing to an unaligned address. Instead, the store simply always fails.
> > This is bad because most atomic functions are written to retry upon a
> failed
> > store, under the assumption they were preempted. These two circumstances
> > combine to where your program will go into an infinite loop if you
> attempt
> > to atomically store to an unaligned address. Oops.
>
> thanks,
> Daniel.
>
Thanks Daniel,
My bad, I was trying to connect the page fault explained before that
paragraph and this one.
Hence I got confused,again thanks for clarifying it.



-- 
With Regards
Subin Gangadharan

Everything should be made as simple as possible,but not simpler.
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