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=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 C87E0C4360C for ; Thu, 26 Sep 2019 19:33:59 +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 97CE6217F4 for ; Thu, 26 Sep 2019 19:33:59 +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="G+wSgQU6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97CE6217F4 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]:43664 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iDZWY-0005ZW-D2 for qemu-devel@archiver.kernel.org; Thu, 26 Sep 2019 15:33:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48561) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iDZ2U-00057C-1p for qemu-devel@nongnu.org; Thu, 26 Sep 2019 15:02:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iDZ2S-0001Qb-Db for qemu-devel@nongnu.org; Thu, 26 Sep 2019 15:02:53 -0400 Received: from mail-wr1-x441.google.com ([2a00:1450:4864:20::441]:45211) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1iDZ2S-0001P0-4t for qemu-devel@nongnu.org; Thu, 26 Sep 2019 15:02:52 -0400 Received: by mail-wr1-x441.google.com with SMTP id r5so3658991wrm.12 for ; Thu, 26 Sep 2019 12:02:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version:content-transfer-encoding; bh=5SMI6xGAzqDdDwn+k9vtD4cATFgG80u6NgLpli1Q3iU=; b=G+wSgQU6s12Y/BU0/PL8j2fj1lK8e2PIPF/52IXpImpXNq6T3Xrnby9qGywj6MpL0R sJsFlhbWk5485o8OGrdNskpfcKHBthOn/FpDHcS/8agrXxr98XZ19bL8GyywBsNtMWNn 6eol6K9o7aCjsS2Vql0CoRvoDANl1dvk0uUDjP6mdquX6O7c6yXAvuLQY4LqQFVER3MK N8oSMrLVmGlWOkihcuFkiO1tekTVd2H/5JMfKKS4240jdUaksnhLjOgRiiMi8znBZBw2 9Ej+D+dfAwvz/C/PKA+iXuAZU0p9diS/5uv06IArc9DsIxfEzoBx2XndJcuASihVil7x jPXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version:content-transfer-encoding; bh=5SMI6xGAzqDdDwn+k9vtD4cATFgG80u6NgLpli1Q3iU=; b=CSEmddDzXOFYnfbCvNIcm6sdJoCexi2vNAR4bFxO3599UjCOmgYVJOQm+oC3wFFib2 GC3jl7om98+gAA6e8kZnMkj4ZmB4yuPBmtTkbnL02CAjUKLGPqU/3FxSGeEvLUtKAezX hoKxPNv0B9P+40gSKgss1/aJFTYjNqWJBjRudaFJ+WisMMCvVM8wKszvbDiFAwVbGJlK RDCHAj9BkqPy9r79hHpWIXwjhYGwJ+6uvuVn2BOpnulLoSNSBu2bdwFaE+xOxpLCRTqx u9iAm96o+fzrSs/zQUFBzb6bZE4qF46o/wsXbM7q/cXKJo0WuMqe5vzvrEMKiUAtR53H NVGA== X-Gm-Message-State: APjAAAXXO72bqCq5/j0i5CMN3tG4DqIuD8NdoHAVC4mDLfohTaNEA8XY Ay4/iIq4FHxw47aPlW2thy0/5Q== X-Google-Smtp-Source: APXvYqw0Rz5FY5mMBC8SqbdHOlCzcwTJTZ/6gkqWWoZUGIT+YVr0dfLRjwBS6+nNqspm7+GnQNFJFw== X-Received: by 2002:adf:9c88:: with SMTP id d8mr925wre.364.1569524570550; Thu, 26 Sep 2019 12:02:50 -0700 (PDT) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id v16sm210581wrt.12.2019.09.26.12.02.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Sep 2019 12:02:49 -0700 (PDT) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 855A51FF87; Thu, 26 Sep 2019 20:02:48 +0100 (BST) References: <20190925233013.6449-1-alex.bennee@linaro.org> <20190926125817.GB19660@redhat.com> <19efe3ee-a532-cf66-a5a7-03a7c053737c@redhat.com> <87d0fn9ix8.fsf@linaro.org> User-agent: mu4e 1.3.4; emacs 27.0.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: Alistair Francis Subject: Re: [RFC PATCH] configure: deprecate 32 bit build hosts In-reply-to: Date: Thu, 26 Sep 2019 20:02:48 +0100 Message-ID: <878sqaanjb.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:4864:20::441 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: Peter Maydell , Thomas Huth , =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Richard Henderson , QEMU Developers , qemu-discuss , Christian Borntraeger , qemu-s390x , qemu-arm , "open list:New World" , "open list:RISC-V" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Alistair Francis writes: > On Thu, Sep 26, 2019 at 8:41 AM Alex Benn=C3=A9e = wrote: >> >> >> Thomas Huth writes: >> >> > On 26/09/2019 15.46, Christian Borntraeger wrote: >> >> >> >> >> >> On 26.09.19 14:58, Daniel P. Berrang=C3=A9 wrote: >> >>> On Thu, Sep 26, 2019 at 08:50:36AM +0100, Peter Maydell wrote: >> >>>> On Thu, 26 Sep 2019 at 00:31, Alex Benn=C3=A9e 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 gue= st 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. >> >>> >> >>> What if the kernel is waiting for QEMU to drop support too ;-P >> >> >> >> For what its worth on kvm/s390 we never cared about implementing >> >> 32 bit. >> > >> > Looking at tcg/s390/tcg-target.inc.c : >> > >> > ... >> > /* We only support generating code for 64-bit mode. */ >> > #if TCG_TARGET_REG_BITS !=3D 64 >> > #error "unsupported code generation mode" >> > #endif >> > ... >> > >> > ... it seems to me that TCG does not support 32-bit on s390 either. I >> > think we can remove s390 (32-bit) from the list completely? >> >> It's the same for riscv32 I think. > > I think riscv32 host *should* work, although I don't think it was ever > tested. You certainly don't support oversized guests: /* We don't support oversize guests */ QEMU_BUILD_BUG_ON(TCG_TARGET_REG_BITS < TARGET_LONG_BITS); > > Considering that we have enough trouble keeping the riscv32 kernel > booting it's probably ok to drop it from QEMU. > > Alistair > >> >> > >> > Thomas >> >> >> -- >> Alex Benn=C3=A9e >> -- Alex Benn=C3=A9e