Re: hf/sf [Was Re: CVS commit: pkgsrc/misc/raspberrypi-userland]

[Matt Thomas <matt%3am-software.com@localhost>]

On Nov 10, 2013, at 12:57 PM, Justin Cormack 
<justin%specialbusservice.com@localhost> wrote:

> On Sun, Nov 10, 2013 at 7:38 PM, Alistair Crooks <agc%pkgsrc.org@localhost> 
> wrote:
>> On Sun, Nov 10, 2013 at 04:56:04AM +0000, Jun Ebihara wrote:
>>> Module Name:  pkgsrc
>>> Committed By: jun
>>> Date:         Sun Nov 10 04:56:04 UTC 2013
>>> 
>>> Modified Files:
>>>     pkgsrc/misc/raspberrypi-userland: Makefile
>>> 
>>> Log Message:
>>> support earmhf.
>>> ONLY_FOR_PLATFORM=      NetBSD-*-*arm*
>>> oked by jmcneill.
>> 
>> Thanks for doing this, Jun-san.
>> 
>> But in the big picture, having hf and sf versions of a platform's
>> userland, in the year 2013, is, well, sub-optimal.  I don't think the
>> ramifications of the change were considered in enough detail, and we
>> need to discuss it, before we have to start growing new architectures
>> in pkgsrc for this and that.
>> 
>> Can't we lean on what was done for i386/i387 twenty years ago, and
>> use a userland library to decide whether to use softfloat in the
>> absence of hardware?
>> 
>> So let's discuss...
> 
> armhf is not just about whether there is or is not hardfloat, it is
> also a different ABI. Its more like mips o32 vs n32 in that it is an
> ABI change that requires some hardware requirements too.

Exactly.  with hf, floating point values are passed in floating point
registers.  That can not be hidden via a library (this works on x86
since the stack has all the arguments).