MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

[Sriram Chadalavada]

 Hi Mr. Albas,
     I am porting AX25 applications/tools to Arcturus
 Networks uCdimm (Motorola MC68VZ328) as part of my
 masters project (www.engr.ku.edu/~kutesat). 
 
 I tried to get TCP/IP applications(uClinux) such as
 FTP, SSH working over an AX.25 link but faced kernel
 panics due to memory alignment issues in the mkiss
 driver, whenever (ICMP, TCP) packets were received
 on the relevant 'kiss' interface.

 In consultation with David McCollough
 (Snapgear/cyberguard.com), I have come up with a
 patch(see attachment) to solve the above problem in
 architectures such as m68000 where alignment issues
 are not handled in hardware. 
 
 The solution lies in increasing skbuf size by 1 and
 aligning the layer 3 header by using
 skb_reserve(skb,1). This approach has been used in
 several ethernet drivers to make them work on these
 architectures.
 
 This change is not yet a part of the mkiss driver
 (2.6.11 kernel). PLease let me know if my patch can
 be incorporated into your driver code. The patched
 driver works on both x86 and m68000.
 
 Kindly reply soon and let me know if you have any
 questions.
 
 Thank you,
 Sriram C.
 (University of Kansas, USA)
 
 


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Re: MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

[M Taylor]

On Sun, Apr 24, 2005 at 01:40:43PM -0700, Sriram Chadalavada wrote:
>  
>  In consultation with David McCollough
>  (Snapgear/cyberguard.com), I have come up with a
>  patch(see attachment) to solve the above problem in
>  architectures such as m68000 where alignment issues
>  are not handled in hardware. 
>  
>  The solution lies in increasing skbuf size by 1 and
>  aligning the layer 3 header by using
>  skb_reserve(skb,1). This approach has been used in
>  several ethernet drivers to make them work on these
>  architectures.

I'm sorry, but it looks like the attachment wasn't included or
was stripped off, could  you please send it again or feel free
to mail it to me, and I will make it available on my webserver.

-ve3tix

Re: MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

[M Taylor]

On Sun, Apr 24, 2005 at 01:40:43PM -0700, Sriram Chadalavada wrote:
>  FTP, SSH working over an AX.25 link but faced kernel
>  panics due to memory alignment issues in the mkiss
>  driver, whenever (ICMP, TCP) packets were received
>  on the relevant 'kiss' interface.
> 
>  In consultation with David McCollough
>  (Snapgear/cyberguard.com), I have come up with a
>  patch(see attachment) to solve the above problem in
>  architectures such as m68000 where alignment issues
>  are not handled in hardware. 
  
http://www.privacy.nb.ca/~mctylr/uClinux/mkiss-skb-align.patch

Re: MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

[Jeroen Vreeken]

M Taylor wrote:

>On Sun, Apr 24, 2005 at 01:40:43PM -0700, Sriram Chadalavada wrote:
>  
>
>> FTP, SSH working over an AX.25 link but faced kernel
>> panics due to memory alignment issues in the mkiss
>> driver, whenever (ICMP, TCP) packets were received
>> on the relevant 'kiss' interface.
>>
>> In consultation with David McCollough
>> (Snapgear/cyberguard.com), I have come up with a
>> patch(see attachment) to solve the above problem in
>> architectures such as m68000 where alignment issues
>> are not handled in hardware. 
>>    
>>
>  
>http://www.privacy.nb.ca/~mctylr/uClinux/mkiss-skb-align.patch
>  
>
It looks ok, but there are some unneeded whitespace changes in your patch...
And on a personal note I like comments in C style more than the C++ 
style you use. /* ... */ instead of // ...
But that might be just me :)

Jeroen

Re: MKISS DRIVER PATCH - for layer 3 longword alignment in m68000

[Sriram Chadalavada]

Mr. Taylor,
 Thanks for posting the patch.

Jeroen,
  The whitespace changes are indeed not necessary. I
should have perhaps got rid of them. 

Cheers,
Sriram

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