On Sat, Aug 6, 2011 at 12:37 PM, Daniel Baluta [off-list ref]wrote:

On Sat, Aug 6, 2011 at 10:17 PM, subin gangadharan
[off-list ref] wrote:

quoted

Hi,
This is a text excerpt from the article [1].
Below paragraph I didn't understand quite well.Mainly in bold

letters.Could

quoted

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).

quoted

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

quoted

store, under the assumption they were preempted. These two circumstances
combine to where your program will go into an infinite loop if you

attempt

quoted

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.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20110806/0dc46c67/attachment.html