Re: Does ARMEL toolchain include NEON support?
On Thu, Feb 28, 2019 at 09:05:04AM +0000, Ian Campbell wrote:
>
> To spell it out: the gist of this is that it isn't possible to provide
> a single arm binary which works well for both armel and armhf (which I
> think is what Jeff is trying/wants to do?).
It is not even possible to provide a single arm binary that runs on
both armel and armhf.[1] It is a different ABI.
> The advice here is to instead ship[0] two binaries -- one targetting v5
> (no neon etc, aka armel in Debian) and another targetting v7 (w/
> possible(? I forget what is optional) neon and other stuff aka armhf in
> Debian and other distros).
The main difference between armel and armhf is not the baseline
(at some point Ubuntu had bumped the armel baseline to v7), the
main difference is that there is no FPU in the armel baseline.
Which also means that floating-point parameters must get passed
in integer registers since there are no floating-point registers
in the ABI.
And if you specify an FPU and use softfp, floating-point parameters
still get passed in integer registers since this is part of the ABI.
-mfloat-abi=hard is the incompatible armhf ABI that passes
floating-point parameters in floating-point registers.
> Ian.
>...
cu
Adrian
[1] but multiarch allows installing both armel and armhf at the
same time
--
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of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
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