[Jack-Devel] ARM: Alignment, Atomicity

Hey all,

so after some further investigation I can report that the reason I was
encountering alignment traps on some version of jackd1 and not on
others was because the ones that were working were compiled with "-O0"
and the broken ones with other optimisation levels (versions compiled
with -O1,2,3 & s encounter alignment traps). Defining the
POST_PACKED_STRUCTURE as empty did not seem to help.

Any insights into why this would be, whether this could be a problem,
even with versions compiled with -O0  and what needs to be done to fix
it are appreciated. Given that undefining the POST_PACKED_STRUCTURE
did not help I guess it bears further investigation into where this is
occurring. I had started to investigate this but set -O0 along with -g
and suddenly my problem had disappeared. I have another go soon. I
guess it is also possible that this is a bug in gcc's optimisation?

After having spent considerable time watching the make output text
scroll by during repeated compiles I actually started to read it (!)
and noticed the warnings about atomicity from
config/cpu/generic/atomicity.h [1].

Are atomic functions in this case not used? Are they needed? Could I
copy the operations jack2 seems to use for ARM [2] to jack1?

Thanks in advance for any thoughts and insights.

Ciao,

Kaspar

[1]https://github.com/jackaudio/jack1/blob/master/config/cpu/generic/atomicity.h#L23
[2]https://github.com/jackaudio/jack2/blob/master/linux/JackAtomic_os.h#L75

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