[Buildroot] [PATCH] package/collectd: Specify correct FP layout for PowerPC

Arnout Vandecappelle arnout at mind.be
Sat Nov 4 20:35:25 UTC 2017



On 03-11-17 00:24, Andrey Smirnov wrote:
>> However, there is a third FP layout called "intswap", and I'm not sure
>> in which situations it should be used. Some additional investigation of
>> collectd configure.ac script is probably needed to understand the
>> AC_RUN_IFELSE() tests it does to figure out what the FP layout is when
>> doing a native build.
>>
> I looked at that part of config.ac when I was debugging the problem
> and AFACT all "intswap()" does is swapping upper and lower 32-bits of
> a 64-bit word. I can't think of an architecture that would require
> such a transformation and commit that introduced that check in
> collectd didn't have any helpful hints either. Can we limit the scope
> of this fix to big vs. little endian the way you suggested and leave
> the "intswap" case out?

 That would be old ARM FP which had mixed-endian doubles? I can't find a good
reference to it, just [1]. I remember from years ago that on ARM I had to do
some weird word-swapping when converting doubles to/from network byte order.

 Regards,
 Arnout


[1] https://en.wikipedia.org/wiki/Endianness#Floating_point

-- 
Arnout Vandecappelle                          arnout at mind be
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