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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF572C02188 for ; Mon, 27 Jan 2025 16:14:30 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tcRkF-0007JV-HI; Mon, 27 Jan 2025 11:13:51 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tcRk8-0007IZ-P9 for qemu-devel@nongnu.org; Mon, 27 Jan 2025 11:13:46 -0500 Received: from mail-pl1-x62f.google.com ([2607:f8b0:4864:20::62f]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1tcRk6-0001KN-RH for qemu-devel@nongnu.org; Mon, 27 Jan 2025 11:13:44 -0500 Received: by mail-pl1-x62f.google.com with SMTP id d9443c01a7336-219f8263ae0so85537155ad.0 for ; Mon, 27 Jan 2025 08:13:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1737994420; x=1738599220; darn=nongnu.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id:from :to:cc:subject:date:message-id:reply-to; bh=qvBQUlFuceOnRV4gwyW6jEWHBYnxnL5ZP+Yw/kJ48x4=; b=hwf7+MifUHuzz+GIvtof/zYo8eEPB1e6qLukeLhTMWLJGri/0NofLDqxyCggnfyp7f YV82ffgbV8tN1dBPESHJ4PRJ04eGWEixTgUF0Jt3avVb+rwrKuukoDiWgi3UYen6RTrL DsVUdDURW10VBDu+XJm/9YLFaetGZrWECuqoWUOnveVExmNFmFhJ7+UZ6kzVFRRWK3if uoFF+ny/lqaf0J20AhQ6mWLWlc7eQziyqJMPajvqW6LgaxfofC+VHf2wSTkyw7yAsv0J NIOOFqVWHKa+d+mgGic1WOfrFQQ1QmRAdjt1+1spw5u2mrgWynvOtx3YRfVV2yXpzZoh 09rQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737994420; x=1738599220; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=qvBQUlFuceOnRV4gwyW6jEWHBYnxnL5ZP+Yw/kJ48x4=; b=O3Ntmk8bF3iG4Gp/9qW50bF5QmRAOu8/FQMo+xW6nA4OeBDRN/WfBvrpOLKEaZXDtt 5FAVYI3xCCJyVF/okAon+SH78fS2jCD3SBlHDqYaKQMHoSPtEzStsFCaoSDBe4uigGX1 9vznNpbrJ4ZXU56QvTMn+Syj2xah+hdik6Wc0CXinsMcIqUxq5nmK5p5lWFSsOR4Ymq0 0+Vkb2Rw03UZkpqVsp6/ZqByqgmgmKFO/K1DHxUBoYt19ahxWsHJbOF5kVDu0765FRkU 9OoBpGR15NKFOkDM3M2bJTa+ePDVkr4Llp03atwKMJ8KVNVQCbcdT7vPmiDMTnjatb9i v3nQ== X-Gm-Message-State: AOJu0YySp4JJmeFdi4SFMixKnEs/i74ogmENP0Cm8nmuNrQRjg7CM8E+ 3kFclUqdV7WdRsdeOmY6Mxta1Sp1HN05Icro2/7GHps/DgV+/ZkrxtPJtH12j5sJ86yQN8UA5m6 O X-Gm-Gg: ASbGnctBwr1ctF5Uj2vvFFcplmFzxYXEJUFEJxu/LRYWrWlyBhhJ36pFCb1nNXn7o05 aosT5FQAfkzO5sfFXmuopVKH0hLowZ1yhiMkO84MCgLAT9/tJQtAnMIFm2CBfx3A68/TLiVW4TQ 3g26Ue67Kb/FxirscjQxSO4+HqCSlbBx8SIrcCCPEIQJEc8nNDXsk/V/DNfxPAhXVbbwZkxoAhI MblARUNfb1S3fNA1ThH4p+VZjVUdj63vH74ny5glWvO1d8LJ5/SCEnnIF29iX7+yREBBhjXnJ8I riOdZ2Vo1q0RAfrjIg3juTZaz1tMYyXWonVUbH74BJarHCg= X-Google-Smtp-Source: AGHT+IGLyF4dF6fQ+7dnDzVrV8rHJBrILeMFxXk3M8srEvcHPMMYAIXCLBye6vPS5nE5VIkAvnpNcg== X-Received: by 2002:a17:903:41c4:b0:216:2259:a4bd with SMTP id d9443c01a7336-21c3562a640mr574924945ad.52.1737994419839; Mon, 27 Jan 2025 08:13:39 -0800 (PST) Received: from [192.168.0.4] (174-21-71-127.tukw.qwest.net. [174.21.71.127]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21da3d9e216sm66155755ad.21.2025.01.27.08.13.39 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Jan 2025 08:13:39 -0800 (PST) Message-ID: <09e353a6-026d-4966-88ab-c4b300e3524f@linaro.org> Date: Mon, 27 Jan 2025 08:13:37 -0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] target/arm: Deprecate iwMMXt emulation and associated CPUs To: qemu-devel@nongnu.org References: <20250127112715.2936555-1-peter.maydell@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: <20250127112715.2936555-1-peter.maydell@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::62f; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x62f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 1/27/25 03:27, Peter Maydell wrote: > This patchset marks all the CPUs that support iwMMXt as deprecated, > because I don't believe anybody is using them, and we have no way to > test the thousands of lines of code we have that's only there for > iwMMXt emulation. (See for instance the recent thread where a patch > was submitted to fix an issue detected by a static analyzer: we > didn't take it, largely because we had no way to know if the > behaviour change the patch would produce was correct or not.) > > The pxa2xx CPUs are now only useful with user-mode emulation, because > we dropped all the machine types that used them in 9.2. (Technically > you could alse use "-cpu pxa270" with a board model like versatilepb > which doesn't sanity-check the CPU type, but that has never been a > supported config.) > > To use them (or iwMMXt emulation) with QEMU user-mode you would need > to explicitly select them with the -cpu option or the QEMU_CPU > environment variable, because the '-cpu max' default CPU does not > include iwMMXt emulation. A google search finds no examples of > anybody doing this in the last decade. > > I asked some of the Linaro GCC folks if they were using QEMU to test > their iwMMXt codegen, or knew anybody doing that upstream, and the > answer was "no". In fact, GCC is in the process of dropping support > for iwMMXt entirely. > > We have one test case in check-tcg which purports to be checking > iwMMXt. In fact it is doing no such thing: it runs the test without > selecting an iwMMXt CPU, which means the iwMMXt insns are interpreted > as FPA11 insns by the linux-user emulate_arm_fpa11() code. So the test > prints garbage and then succeeds anyway. Modern distro toolchains > can't generate a binary that will run with -cpu pxa270 (because their > crt startup code uses Thumb insns); rather than putting in a lot of > effort trying to salvage the test case to really test a feature we've > deprecated, I opted to just remove the test. Reviewed-by: Richard Henderson r~