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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 D0ADBC10DCE for ; Wed, 18 Mar 2020 14:44:16 +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 9714520770 for ; Wed, 18 Mar 2020 14:44:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DkKToPyG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9714520770 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51748 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEZvb-000557-Ql for qemu-devel@archiver.kernel.org; Wed, 18 Mar 2020 10:44:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36185) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jEZql-000683-RG for qemu-devel@nongnu.org; Wed, 18 Mar 2020 10:39:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jEZqk-0004fq-Km for qemu-devel@nongnu.org; Wed, 18 Mar 2020 10:39:15 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:33701) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jEZqk-0004de-Gq for qemu-devel@nongnu.org; Wed, 18 Mar 2020 10:39:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584542354; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9kZQwjmQy0wRv9ytBq/y9fO7Pf7M8IAux1EHXGFKnvI=; b=DkKToPyGVnUQVkTFqXvPQgtZreA6cMzLVKDVE70TqLK0oBZPhh++sL2nWQFuzbnwiJEJGR w2wOrMdDfAWB5CjPjPS5VeXbU+sFisGFWQMdjSszPTBZJAsiZDe1En+73BbXziBjl0EWDI Z5rfzhY+soGlaqR0o/iofp1zMICy19U= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-274-w0jYwtHWMiebnn8Lp-nlVA-1; Wed, 18 Mar 2020 10:39:07 -0400 X-MC-Unique: w0jYwtHWMiebnn8Lp-nlVA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 02AA818B9FC1; Wed, 18 Mar 2020 14:39:06 +0000 (UTC) Received: from [10.3.112.193] (ovpn-112-193.phx2.redhat.com [10.3.112.193]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 637465D9E5; Wed, 18 Mar 2020 14:39:02 +0000 (UTC) Subject: Re: [RFC (fix for 5.0?)] block/io: do not do pointer arithmetic on void * To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Vladimir Sementsov-Ogievskiy References: <20200318142253.2809-1-vsementsov@virtuozzo.com> <20200318142654.GH2173309@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Wed, 18 Mar 2020 09:39:01 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200318142654.GH2173309@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 63.128.21.74 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: kwolf@redhat.com, fam@euphon.net, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/18/20 9:26 AM, Daniel P. Berrang=C3=A9 wrote: > On Wed, Mar 18, 2020 at 05:22:53PM +0300, Vladimir Sementsov-Ogievskiy wr= ote: >> Signed-off-by: Vladimir Sementsov-Ogievskiy >> --- >> >> Hi all! >> >> C standard doesn't allow pointer arithmetic on void *. >> Still, gcc allows it as an extension: >> https://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Pointer-Arith.html >> >> I can create a series of patches like this. Do we need it? >=20 > I don't think so, we only care about gcc & clang. Still, if all supported compilers support the extension, then our=20 CODING_STYLE.rst should mention that it is safe to rely on the extension. >=20 >> Also, where is documented which compilers are supported by Qemu? >=20 > It is checked in configure - gcc 4.8 or clang 3.4 or xcode clang 5.1 >=20 --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org