On Fri, Oct 05, 2012 at 07:24:44AM -0500, Rob Herring wrote:
On 10/05/2012 03:24 AM, Russell King - ARM Linux wrote:
Does it matter? I'm just relaying the argument against adding __packed which was used before we were forced (by the networking folk) to implement the alignment fault handler.
It doesn't really matter what will be accepted or not as adding __packed to struct iphdr doesn't fix the problem anyway. gcc still emits a ldm. The only way I've found to eliminate the alignment fault is adding a barrier between the 2 loads. That seems like a compiler issue to me if there is not a better fix.
Even so, please test the patch I've sent you in the sub-thread - that needs testing whether or not GCC is at fault. Will's patch to add the warnings _has_ uncovered a potential issue with the use of __get_user() in some parts of the ARM specific kernel, and I really need you to test that while you're experiencing this problem.