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=-5.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,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 CF6BDC433F5 for ; Tue, 21 Sep 2021 02:03:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6689610A8 for ; Tue, 21 Sep 2021 02:03:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242280AbhIUCEi (ORCPT ); Mon, 20 Sep 2021 22:04:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234662AbhIUBpM (ORCPT ); Mon, 20 Sep 2021 21:45:12 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21645C05937A; Mon, 20 Sep 2021 14:14:14 -0700 (PDT) Received: by mail-pf1-x436.google.com with SMTP id m26so17470304pff.3; Mon, 20 Sep 2021 14:14:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=wJbe26PbHhpGOrBm34WfP3EQpBDDdiCtuFeJHFErXao=; b=XsOg/+RTS1dlQNb9LQapBJTEFbCTAMTz0fxmiMQT2IuwKXO/HGmAf4Tv+771pP9njY nMxicCI6TJ7kfiCsL1P9Iq9ia/ZdNxasSfvohF+q+MAN/DS82gHpFxtGPjZ2VVFzOSMB qFKTjVaN6yM9ZYqWlNSs8iqKIhrcc902zTIgS3z/24bT9yGe6DQpfxbfjfW/sH7chB8w hwgxBaJWDPs//QlPZB/rbFStytxNc8xWs+xR8cuUN2HsumNl5VkD7mI713EsofTW81i7 q8WkCNTCpbd5NXvqfelOHpsKEV6NKhzoLcqcVsiXPz52vQCKD9vOQ3xesM06Sh4fahOQ vN2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=wJbe26PbHhpGOrBm34WfP3EQpBDDdiCtuFeJHFErXao=; b=pAB9PV995tNH42WiD5igGo40ltmnpk9Xv91Q3pAF63CML4jxpOugaNr5qWKywhGRvA VDKu0I1V6LIKWqiT3kVJZv5YCtbJZ39nIQXIRD3NzhRIiUedu4KK4YpHZb3WnF+T+7xJ by1KLMFNzRO8GcVO3/lmXK5UPhb7Giw416PwcLGYmk8y9r+VXjsUJBXMPJMwqSZiJGAl 6BcX0zoCA8G1ExPpySukgItKqMy+y7QwUORUyqMhywJJEAPsk0fN1UyO3yjzsgo9i54M UNqvjgwRBEjOAxqQZVZ3pwy5aWruqgpkAzb8vSWNBeW0yNSdbBrcLZGtrc9N9bQliU45 wqIQ== X-Gm-Message-State: AOAM5301iSS+dii+GIlmAo3nNVUDSOEVboQCHrY3kfo3/aoRHLiV7as/ 6rokvisuVeFjGwoMlqM82jU= X-Google-Smtp-Source: ABdhPJxT+Kq7mMohFE4vU+4/4A3kHTJgOAReFUeXiGCwjRSGFhNml42MoQBZbYpHGt5HUM9KI8UGng== X-Received: by 2002:a05:6a00:c3:b0:43d:e6be:b2a6 with SMTP id e3-20020a056a0000c300b0043de6beb2a6mr27203762pfj.34.1632172453197; Mon, 20 Sep 2021 14:14:13 -0700 (PDT) Received: from [192.168.1.11] ([71.212.134.125]) by smtp.googlemail.com with ESMTPSA id p24sm14925238pfh.136.2021.09.20.14.14.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Sep 2021 14:14:12 -0700 (PDT) Sender: Richard Henderson Subject: Re: [PATCH V3 14/22] LoongArch: Add signal handling support To: Huacai Chen , Arnd Bergmann Cc: "Eric W. Biederman" , Huacai Chen , Andy Lutomirski , Thomas Gleixner , Peter Zijlstra , Andrew Morton , David Airlie , Jonathan Corbet , Linus Torvalds , linux-arch , "open list:DOCUMENTATION" , LKML , Xuefeng Li , Yanteng Si , Jiaxun Yang References: <20210917035736.3934017-1-chenhuacai@loongson.cn> <20210917035736.3934017-15-chenhuacai@loongson.cn> <87tuii52o2.fsf@disp2133> From: Richard Henderson Message-ID: Date: Mon, 20 Sep 2021 14:14:10 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/19/21 7:36 PM, Huacai Chen wrote: > Hi, Arnd, > > On Sun, Sep 19, 2021 at 5:59 PM Arnd Bergmann wrote: >> >> On Sat, Sep 18, 2021 at 9:12 AM Huacai Chen wrote: >>> On Sat, Sep 18, 2021 at 5:10 AM Eric W. Biederman wrote: >>>> For example does LoongArch have a version without built in floating >>>> point support? >>> >>> Some of these structures seems need rethinking, But we really have >>> LoongArch-based MCUs now (no FP, no SMP, and even no MMU). >> >> NOMMU Linux is kind-of on the way out as interest is fading, so I hope you >> don't plan on supporting this in the future. >> >> Do you expect to see future products with MMU but no FP or no SMP? > OK, we will not care no-MMU hardware in Linux, but no-FP and no-SMP > hardware will be supported. Please consider requiring the FP registers to be present even on no-FP hardware. With this plus the FP data movement instructions (FMOV, MOVGR2FR, MOVFR2GR, FLD, FST), it is possible to implement soft-float without requiring a separate soft-float ABI. This can vastly simplify compatibility and deployment. r~