Date: Fri, 24 Feb 2017 09:56:03 -0800 From: John Baldwin <jhb@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: "Rodney W. Grimes" <freebsd-rwg@pdx.rh.cn85.dnsmgr.net>, 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 Message-ID: <2826708.tPzGBbFfxk@ralph.baldwin.cx> In-Reply-To: <20170224171405.GX2092@kib.kiev.ua> References: <201702241602.v1OG21SM034524@repo.freebsd.org> <201702241653.v1OGrRTJ028384@pdx.rh.CN85.dnsmgr.net> <20170224171405.GX2092@kib.kiev.ua>
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On Friday, February 24, 2017 07:14:05 PM Konstantin Belousov wrote: > 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. I think it was gone in 5.0. > > 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. Yes, we effectively require an FPU on i386. I'd be tempted to start requiring a built-in FPU (so INT 16 vs IRQ 13) so we could further reduce diffs with amd64 and eventually have an "x86" fpu.c. That would only drop support for systems using a 486sx with an external FPU. Those systems are probably happier running FreeBSD 4.x than 12 anyway. -- John Baldwin
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