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

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

[Marek Lindner]

Greg,

> The patch is only compile-tested.

[..]

> diff --git a/drivers/staging/batman-adv/main.c
> b/drivers/staging/batman-adv/main.c index 0587940..6ea6420 100644
> --- a/drivers/staging/batman-adv/main.c
> +++ b/drivers/staging/batman-adv/main.c
> @@ -149,7 +149,7 @@ void dec_module_count(void)
> 
>  int compare_orig(void *data1, void *data2)
>  {
> -	return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
> +	return (compare_ether_addr(data1, data2) == 0 ? 1 : 0);
>  }

I'm wondering why you accepted this patch despite the raised objections 
regarding alignment problems. [1][2]
Is there something you know that we overlooked ? We haven't heard from Thomas 
or you since the alignment question came on the table. 

Cheers,
Marek

[1]https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2010-November/003640.html
[2]https://lists.open-mesh.org/pipermail/b.a.t.m.a.n/2010-November/003643.html

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

[Greg KH]

On Wed, Nov 10, 2010 at 11:17:03AM +0100, Marek Lindner wrote:
> 
> Greg,
> 
> > The patch is only compile-tested.
> 
> [..]
> 
> > diff --git a/drivers/staging/batman-adv/main.c
> > b/drivers/staging/batman-adv/main.c index 0587940..6ea6420 100644
> > --- a/drivers/staging/batman-adv/main.c
> > +++ b/drivers/staging/batman-adv/main.c
> > @@ -149,7 +149,7 @@ void dec_module_count(void)
> > 
> >  int compare_orig(void *data1, void *data2)
> >  {
> > -	return (memcmp(data1, data2, ETH_ALEN) == 0 ? 1 : 0);
> > +	return (compare_ether_addr(data1, data2) == 0 ? 1 : 0);
> >  }
> 
> 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.

thanks,

greg k-h

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

[Sven Eckelmann]

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

[Greg KH]

On Wed, Nov 10, 2010 at 05:46:37PM +0100, Sven Eckelmann wrote:
> 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.

Oops, my fault, I've now reverted this patch, sorry about that.

thanks,

greg k-h

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

[Tobias Klauser]

On 2010-11-10 at 17:46:37 +0100, Sven Eckelmann <sven.eckelmann@gmx.de> wrote:
> > 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.

I'll send an updated patch, leaving out the compare_ether_addr part.

Cheers
Tobias

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

[Marek Lindner]

On Thursday 11 November 2010 02:11:37 Greg KH wrote:
> > 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.
> 
> Oops, my fault, I've now reverted this patch, sorry about that.

No problem, that can happen.

Thanks,
Marek

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

[Marek Lindner]

Hi,

> Hello, im a BATMAN user and also a member of the website. Im doing a
> project using BATMAN for MANET.I actually plan to modify codes from
> batman-0.3.2, to be able to modify the packet header and send the codes
> between notebooks. Any kind soul able to point me in the direction to look
> at? Which codes do i specifically modify?

you wish to modify the batman daemon sources ? What kind of changes do you 
have in mind ?

Note that HTML mails are not blocked on the batman mailing list.

Cheers,
Marek

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

[Marek Lindner]

Tobias,

> I'll send an updated patch, leaving out the compare_ether_addr part.

not necessary anymore. Today I included a patch from Sven that does the job.

Thanks for bringing this up,
Marek