From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/9288 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: Re: musl libc for PPC64 Date: Mon, 8 Feb 2016 18:29:45 -0500 Message-ID: <20160208232945.GE9349@brightrain.aerifal.cx> References: <20160208161758.GG9915@port70.net> <20160208165143.GA9349@brightrain.aerifal.cx> <20160208201802.GB9349@brightrain.aerifal.cx> <20160208225921.GD9349@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1454974201 26691 80.91.229.3 (8 Feb 2016 23:30:01 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 8 Feb 2016 23:30:01 +0000 (UTC) Cc: musl@lists.openwall.com To: David Edelsohn Original-X-From: musl-return-9301-gllmg-musl=m.gmane.org@lists.openwall.com Tue Feb 09 00:30:01 2016 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1aSvFo-00062T-Ts for gllmg-musl@m.gmane.org; Tue, 09 Feb 2016 00:30:01 +0100 Original-Received: (qmail 30444 invoked by uid 550); 8 Feb 2016 23:29:58 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 30425 invoked from network); 8 Feb 2016 23:29:58 -0000 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:9288 Archived-At: On Mon, Feb 08, 2016 at 06:24:27PM -0500, David Edelsohn wrote: > You *can* use v2 ABI for BE, but there is no software to run. There > is no software or ecosystem or operating system that runs v2 ABI BE. > It's not a hardware limitation, but there is no environment for the > alternate combination. Indeed. At this point there's no musl ecosystem for ppc64 at all though; whatever we add is a fresh start. > >> IBM has announced that the next generation of the processor will > >> support native IEEE128 floating point in hardware. There will be > >> software emulation for the current processors. Support is included in > >> the forthcoming GCC 6. > > > > OK. Does the existing software emulation properly update the hardware > > floating point status (exception flags) and use the rounding mode? > > I'm not sure what you mean. The software emulation assumes the > hardware support is not present. It doesn't mirror back the state to > the processor in 64 bit mode. But the emulation is fully IEEE128 > compliant. if fesetround(FE_DOWNWARD) succeeds but then long double math still rounds to nearest, that's not IEEE compliant. The big obstacle to having fenv with softfloat on fully-softfloat archs is the lack of register state for the rounding mode and exception flags, so it should be possible to do this right as long as the cpu has status/mode registers for single/double, which the soft-quad code can then access/set. If this isn't done right already we could either try to get it fixed in libgcc or punt and go with ld64. Rich