From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6302FC433E0 for ; Wed, 5 Aug 2020 20:49:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 415DE2075A for ; Wed, 5 Aug 2020 20:49:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726155AbgHEUt6 (ORCPT ); Wed, 5 Aug 2020 16:49:58 -0400 Received: from out28-74.mail.aliyun.com ([115.124.28.74]:59095 "EHLO out28-74.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725372AbgHEUt5 (ORCPT ); Wed, 5 Aug 2020 16:49:57 -0400 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.1063297|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_regular_dialog|0.100094-0.014619-0.885287;FP=0|0|0|0|0|-1|-1|-1;HT=e02c03268;MF=zhouyu@wanyeetech.com;NM=1;PH=DS;RN=13;RT=13;SR=0;TI=SMTPD_---.ID03Ai1_1596660592; Received: from 192.168.10.205(mailfrom:zhouyu@wanyeetech.com fp:SMTPD_---.ID03Ai1_1596660592) by smtp.aliyun-inc.com(10.147.41.121); Thu, 06 Aug 2020 04:49:53 +0800 Subject: Re: [PATCH] MIPS: Provide Kconfig option for default IEEE754 conformance mode To: Jiaxun Yang , "Maciej W. Rozycki" , Serge Semin Cc: Serge Semin , linux-mips@vger.kernel.org, Thomas Bogendoerfer , Paul Burton , Huacai Chen , Zhou Yanjie , =?UTF-8?B?5ZGo55Cw5p2wIChaaG91IFlhbmppZSk=?= , Liangliang Huang , linux-kernel@vger.kernel.org, "Maciej W. Rozycki" References: <20200731041018.1381642-1-jiaxun.yang@flygoat.com> <20200731061702.fxdfyxpvd6qrhoql@mobilestation> From: Zhou Yanjie Message-ID: Date: Thu, 6 Aug 2020 04:49:52 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org 在 2020/8/3 下午5:01, Jiaxun Yang 写道: > > > 在 2020/8/3 上午5:46, Maciej W. Rozycki 写道: >> On Fri, 31 Jul 2020, Serge Semin wrote: >> >>>> Requested by downstream distros, a Kconfig option for default >>>> IEEE754 conformance mode allows them to set their mode to >>>> relaxed by default. >>> That's what should have been here in the first place. Thanks! >>   Well, originally plans were there to have NaN interlinking implemented >> and no such mess or desire for hacks like one here would result.  Cf.: >> >> , >> , >> >> and then: >> >> , >> , >> , >> . >> >> You could well pick this work up and complete it if you like. Final >> conclusions for further work were made here: >> >> , >> , >> . >> >>   In the relaxed mode math programs may produce wrong results unless you >> rebuild all your software for the correct NaN mode for the hardware used > > Unfortunately most of the hardware guys didn't understood the > difficulty here. > They decided to implement their hardware (P5600 & LS3A4000) as NaN2008 > only. > All SoCs based on Ingenic XBurst2 CPU core are also NaN2008 only. > I was thinking about let Kernel drop SIGFPE exception was caused by > mismatched NaN, > as most applications don't rely on signaling NaN, but it is still a > dirty hack. Not a good > idea in general. > > Thanks. > > - Jiaxun > >> (in which case you don't need the relaxed setting in the first place). > >> >>    Maciej