[En-Nut-Discussion] ARM GCC 4.4 Alignment Problems

[Ole Reinhardt]

Hi!

> What should this handler do in addition to what is already implemented
> in nut/arch/arm/debug?

It would not just call the debug code and produce a stack trace but will
"correct" the unaligned access. Let me use Bernds words:

"You either load an aligned 32 bit value into a register or load two
partial data into two registers, then shift and aggregate them."

This fixup needs to be done for every memory access instruction.

The program would not crash and will only work a little slower. For sure
unaligned access should be reported together with the current pc value
to allow easy error detection and correction by the developer.

A quite complex implementation can be found in the linux kernel at 

arch/arm/mm/alignment.c 

Bye,

Ole

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