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Date: Fri, 24 Feb 2017 19:14:05 +0200
From: Konstantin Belousov <kostikbel@gmail.com>
To: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
Cc: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject: Re: svn commit: r314210 - in stable/11/sys: conf i386/conf i386/i386
 i386/include i386/isa i386/linux x86/acpica x86/x86
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On Fri, Feb 24, 2017 at 08:53:27AM -0800, Rodney W. Grimes wrote:
> > Author: kib
> > Date: Fri Feb 24 16:02:01 2017
> > New Revision: 314210
> > URL: https://svnweb.freebsd.org/changeset/base/314210
> > 
> > Log:
> >   MFC r313154:
> >   For i386, remove config options CPU_DISABLE_CMPXCHG, CPU_DISABLE_SSE
> >   and device npx.
> 
> Um, why?????   Makes it much easier to test soft float if we can remove
> the npx device.   Or has soft float support died yet again?
Soft float was removed very long time ago.

> 
> Yes, an i386 without an FPU is anchient by why are we removing working
> functionality?
This question makes an impression that you think that kernel would not
boot on a machine without FPU.  The code to tolerate such configuration
is there, but it is not tested for obvious reasons.

Completely different issue is that userspace requires FPU and e.g. /bin/sh
traps on the next setjmp(3) call.

Also, we do not run on real 386, only on 486+, and there was probably only
Intel 486SX CPU model which has all 486 features but no FPU.