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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 33FF9C4360C for ; Thu, 26 Sep 2019 17:25:12 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id EDBD6222C7 for ; Thu, 26 Sep 2019 17:25:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="HOUa2Yg3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDBD6222C7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41564 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iDXVu-0003Bt-Vj for qemu-devel@archiver.kernel.org; Thu, 26 Sep 2019 13:25:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53745) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iDXJO-0000jY-Fh for qemu-devel@nongnu.org; Thu, 26 Sep 2019 13:12:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iDXJL-0007Lb-8L for qemu-devel@nongnu.org; Thu, 26 Sep 2019 13:12:12 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:33952) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1iDXJL-0007KL-3B for qemu-devel@nongnu.org; Thu, 26 Sep 2019 13:12:11 -0400 Received: by mail-pf1-f196.google.com with SMTP id b128so2216706pfa.1 for ; Thu, 26 Sep 2019 10:12:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=subject:to:cc:references:from:openpgp:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=9SeAmBswGPUU/7s1XP2AkyYn8Y1JWganLEKiKSJadmw=; b=HOUa2Yg3NKZH23KPRP27i1SuQYGPZ0ioWma8hZRodfHbySuHPCAeela1Euern5q3ra Fz7qksFFNuCiBRxT3m+9l3nJxQMAUO5CfpSYeiI5E93O1tblteC0Q4XKWS9ag7mCsfS4 ATGtHARHsrR8L1EnufpviMg5KfYZco+QKqOPcFoypHY8MW8SdspJPUSL1Dr32OUu0C0s xWs9W1brPzf+GqH2vkGXX3z9mAwfQAlkg30XaODDZdu12DKT10IPcScdBr3jbZ/SsPRM /fl4oDZY2MaCDxR7WeobbISX9f9Z+bBDTURjo7oh3PF7CBnkZjE+ivMuYISqSqAaGmrG +j2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=9SeAmBswGPUU/7s1XP2AkyYn8Y1JWganLEKiKSJadmw=; b=jgurqGCl01bI0Ndcc/MbQYuwRA4m0bgzYfG/h3V1YNemXOkIPQBP6jPNsPX5P+iy+f HYOUgBfN+B2fm65rWbHNrebtYeHwVqWaXo2L+ED4uqcpXSqwDq8ldJ1Zb5fsCS/kIRfD c7IM8WkNHKM+G+db3BmA6EtIn9MGKWEJT7AMjXYbE2A1jFL4tRB/F/FCSCIeseqp/zho D/DBKVFv21zSMRupZjHvZQDu+28CS9rTdvl9bSnC7h2cNAzE+9yf4Npn13Xo2+Ie8x6h Aikq8+cI9qFndj5TvwuIt3Ge397zaGdsN2rvt9+kBssPNusvWbfsBPpK3KySCHz2KX3s OmRw== X-Gm-Message-State: APjAAAU+P7cx9UpLQ858PmmUHB7o/tLkSYAWY0BsdBFsIojlsAG9P5SN ZzaKLvrSbrRzkxAEJv4fFx4FmQ== X-Google-Smtp-Source: APXvYqwuZdwdokxX7L2XLlS5TdmlGrJY1vSMMT7B6mTyEQmDtdAcjlg5kPy2z3STwqoZ2VqMANAWQg== X-Received: by 2002:a62:8209:: with SMTP id w9mr4981825pfd.112.1569517869117; Thu, 26 Sep 2019 10:11:09 -0700 (PDT) Received: from [172.20.32.216] ([12.157.10.114]) by smtp.gmail.com with ESMTPSA id c128sm4188974pfc.166.2019.09.26.10.11.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 26 Sep 2019 10:11:07 -0700 (PDT) Subject: Re: [RFC PATCH] configure: deprecate 32 bit build hosts To: Peter Maydell , =?UTF-8?Q?Alex_Benn=c3=a9e?= References: <20190925233013.6449-1-alex.bennee@linaro.org> From: Richard Henderson Openpgp: preference=signencrypt Message-ID: <4512b61a-ed82-e628-88e5-f44ef87c2b50@linaro.org> Date: Thu, 26 Sep 2019 10:11:05 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.210.196 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:RISC-V" , QEMU Developers , qemu-discuss , qemu-s390x , qemu-arm , qemu-ppc@nongnnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/26/19 12:50 AM, Peter Maydell wrote: > On Thu, 26 Sep 2019 at 00:31, Alex Bennée wrote: >> >> The 32 bit hosts are already a second class citizen especially with >> support for running 64 bit guests under TCG. We are also limited by >> testing as actual working 32 bit machines are getting quite rare in >> developers personal menageries. For TCG supporting newer types like >> Int128 is a lot harder with 32 bit calling conventions compared to >> their larger bit sized cousins. Fundamentally address space is the >> most useful thing for the translator to have even for a 32 bit guest a >> 32 bit host is quite constrained. >> >> As far as I'm aware 32 bit KVM users are even less numerous. Even >> ILP32 doesn't make much sense given the address space QEMU needs to >> manage. > > For KVM we should wait until the kernel chooses to drop support, > I think. Agreed. I think this discussion should be more about TCG. >> @@ -745,19 +744,22 @@ case "$cpu" in >> ;; >> armv*b|armv*l|arm) >> cpu="arm" >> - supported_cpu="yes" >> ;; > > I'll leave others to voice opinions about their architectures, > but I still have 32-bit arm in my test set for builds, and > I'm pretty sure we have users (raspi users, for a start). I'd really like to know what raspi users might be using qemu for. Depending on that answer, perhaps it would be sufficient for arm32 tcg to only support 32-bit guests. For context, the discussion that Alex and I were having was about int128_t, and how to support that directly in tcg (especially to/from helpers), and how that might be vastly easier if we didn't have to consider 32-bit hosts. r~