Re: [B.A.T.M.A.N.] patch "staging: batman-adv: Use linux/etherdevice.h address helper functions" added to staging tree

[Sven Eckelmann <sven.eckelmann@gmx.de>]

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On Wednesday 10 November 2010 17:04:55 Greg KH wrote:
> > I'm wondering why you accepted this patch despite the raised objections
> > regarding alignment problems. [1][2]
> 
> Because at the end of that thread, it sounded like you all agreed that
> this patch was acceptable.
> 
> If not, then please let me know and I will revert it.

The end of the thread was that he should remove parts of the patch and resent 
it - or prove that all the data is 2 bytes aligned.


On Wednesday 03 November 2010 11:56:19 Sven Eckelmann wrote:
[...]
> > I don't think they need to be two bytes aligned, but I might be wrong.
> 
> compare_ether_addr uses a two byte pointer to access 3x two bytes. This
> makes it necessary to have all those 3 bytes aligned to 2 byte boundaries.
[correction sent later: "6x two bytes aligned to 2 byte boundaries"]
> Otherwise the compiler has to generate special instructions on
> architectures which don't support loads on non-aligned addresses. Usually
> he doesn't do it unless he has some indications that it is necessary
> (__attribute__ ((packed)) for example).
> 
> There is also documentation available on that topic in
> Documentation/unaligned-memory-access.txt
> 
> And maybe it is good to use is_broadcast_ether_addr, but leave
> compare_ether_addr part open (or prove that we always have those two
> operands correctly aligned).
[...]

None of that happened yet. And yes, this wasn't the last mail we sent to him 
to get some response - no answer till now.

Best regards,
	Sven


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