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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,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 9161CC4361B for ; Fri, 18 Dec 2020 00:15:52 +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 E706823A53 for ; Fri, 18 Dec 2020 00:15:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E706823A53 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43968 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kq3R0-0007q2-Po for qemu-devel@archiver.kernel.org; Thu, 17 Dec 2020 19:15:50 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:46162) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kq3Q9-0007PZ-F7 for qemu-devel@nongnu.org; Thu, 17 Dec 2020 19:14:58 -0500 Received: from mx2.suse.de ([195.135.220.15]:47562) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kq3Q5-0007XH-Pc for qemu-devel@nongnu.org; Thu, 17 Dec 2020 19:14:56 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9B3D8ACF5; Fri, 18 Dec 2020 00:14:51 +0000 (UTC) Subject: Re: dangers of current NEED_CPU_H, CONFIG_SOFTMMU, CONFIG_USER_ONLY From: Claudio Fontana To: Peter Maydell References: <20201211100908.19696-1-cfontana@suse.de> <20201211100908.19696-8-cfontana@suse.de> Message-ID: Date: Fri, 18 Dec 2020 01:14:50 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=195.135.220.15; envelope-from=cfontana@suse.de; helo=mx2.suse.de X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Eduardo Habkost , Alex Bennee , Richard Henderson , QEMU Developers , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/18/20 12:47 AM, Claudio Fontana wrote: > On 12/17/20 11:49 PM, Peter Maydell wrote: >> On Thu, 17 Dec 2020 at 22:45, Claudio Fontana wrote: >>> >>> On 12/17/20 9:15 PM, Peter Maydell wrote: >>>> On Thu, 17 Dec 2020 at 19:46, Claudio Fontana wrote: >>>> Yeah, don't try to ifdef out struct fields in common-compiled code... >>> >>> or should I? Using >>> >>> #ifdef NEED_CPU_H >>> #ifdef CONFIG_SOFTMMU >>> >>> seems to do what I expect. Is it wrong? >> >> I think that gives you two versions of the struct: >> - one seen by compiled-once files and by compiled-per-target softmmu files >> - one seen by compiled-per-target user-only files >> >> Since the user-only target executables link both compiled-per-target >> and compiled-once files I think they end up with different C files >> thinking the same struct has a different layout/size which seems >> like it's going to cause problems. >> >> thanks >> -- PMM >> > > It doesn't with > > #ifdef NEED_CPU_H > #ifdef CONFIG_SOFTMMU > > just double checked the pointers from both files compiled per target and "common"; also all tests are ok. > > It immediately breaks if I replace those two defines with #ifndef CONFIG_USER_ONLY and recompile. > > I thought it was by design, but I guess this is just a "lucky" accident? By lucky accident I mean that CONFIG_SOFTMMU is a check in the positive instead of the #if !defined(CONFIG_USER_ONLY), so it ends up working.. > > Ciao, > > Claudio >