Re: Configuration advice, specifically for arm-cortex-a8

[Erik Leunissen <elns at xs4all dot nl>]

On 02/02/15 23:02, Erik Leunissen wrote:
> I experimented with both "hardware" and "leave to gcc", because of the
> NEON floating-point accelerator, advertised here:
>
>      http://beagleboard.org/BLACK
>
> Whatever choice I make: the resulting toolchains fail if I invoke gcc
> with the option:
>
>      -mfloat-abi=hard

The native gcc on the beagle bone black[*], does not complain on:

    gcc -mfloat-abi=hard -mfpu=neon


So I expected to find a header file "stubs-hard.h" somewhere in the guts 
of it.

Surprise: there isn't any on the entire file system!

Erik.

[*]  part of the pre-installed Debian distribution
--

>   However, the option
>
>      -mfpu=neon
>
> doesn't raise any errors.
>
> That surprises me. Doesn't "NEON floating-point accelerator" imply
> hardware floating point? See also:
>
>
> http://www.eliteraspberries.com/blog/2013/09/cflags-for-numerical-computing-on-the-beaglebone-black.html)
>
>
> What am I missing?
>
>
> Case 2: the cpu
> ===============
> This is a arm-cortex-a8, specifically Sitara AM3358 ARM Cortex-A8.
> What are the pro's and con's of configuring this in ct-ng (with the
> option category "Target optimisations") and leaving it as configurable
> at the gcc command line, using:
>
>      $prefix-gcc -march=armv7-a -mcpu=cortex-a8 -mtune=cortex-a8
>
>
>
> Thanks for sharing any insights,
>
> Erik Leunissen
> --
>
> --
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