[lwip-users] lwip + sam7x = udef exception

[B B]

Hi all,
 
I am currently looking into a problem, where an undef exception occurs. The time in which the exception occurs,
seem to be random from 5 minutes to 1 hour. And i am writing here because this might be a common error/bug in the code.
 
The sam7x features some registers, which contain information about these types of exception, MC_ASR & MC_AASR.
 
The MC_ASR register contains information about the exception type, the following bits were set:
 
- MISADD = 1 => The last aborted access was due to an address misalignment.
 
- ABTSZ = 1 0 => Abort size: Word
 
- ABTTYP = 0 0 => Abort type: Data Read
 
- MST_ARM = 1 => The last aborted access was due to the ARM. 
 
The MC_AASR contains the address of the offending instruction, which in my case is 0x0011117E.
At that address is the following instruction: 
 
adds r4, r3,#0x0
 
This instruction is part of the following statement in the tcp_input function:
 
tcphdr = (struct tcp_hdr *)((u8_t *) p->payload + IPH_HL(iphdr) * 4);
 
How can i make sure that this statement is correctly aligned ?
 
I am also attaching the lwipopts.h file in case that should be needed.
Any insights into this problem is greatly appriciated.
 
Regards,
 
Martin

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lwipopts.h
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