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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 7E906C433DB for ; Sun, 7 Mar 2021 12:37:54 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 2AD9B64E31 for ; Sun, 7 Mar 2021 12:37:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AD9B64E31 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.94506.178082 (Exim 4.92) (envelope-from ) id 1lIsf2-0008TL-96; Sun, 07 Mar 2021 12:37:28 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 94506.178082; Sun, 07 Mar 2021 12:37:28 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lIsf2-0008TE-5J; Sun, 07 Mar 2021 12:37:28 +0000 Received: by outflank-mailman (input) for mailman id 94506; Sun, 07 Mar 2021 12:37:27 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lIsf1-0008T9-1T for xen-devel@lists.xenproject.org; Sun, 07 Mar 2021 12:37:27 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lIsex-0002jp-V4; Sun, 07 Mar 2021 12:37:23 +0000 Received: from 54-240-197-234.amazon.com ([54.240.197.234] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1lIsex-0003sS-Jj; Sun, 07 Mar 2021 12:37:23 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=AMIkYuHXp74v7qOiZccjjE6wmpie7IJ3DHDShXxqeTc=; b=hV+Q3xhlfjLM0K6LbqIxjSKWtK tMebSMjz+WwIK7viiuz3qTzQ95jBSV9vKNuPU+Xz2f9wFTwgLsG8uUILwo31z3MHNRzHEMNuhNjfb oICMj0BLNtr9VmBTYj3QWek33ZbY8uFComFJHOz4ao2j3HFdHaz9N7YV9FhspNrBENgA=; Subject: Re: [PATCH for-4.15] xen: Bump the minimum version of GCC supported to 4.9 (5.1 on arm64) To: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: xen-devel@lists.xenproject.org, Julien Grall , Andrew Cooper , George Dunlap , Ian Jackson , Jan Beulich , Stefano Stabellini , Wei Liu References: <20210306214148.27021-1-julien@xen.org> From: Julien Grall Message-ID: <6d312453-a949-143b-f4a6-e7fac7ef6486@xen.org> Date: Sun, 7 Mar 2021 12:37:21 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Hi Roger, On 07/03/2021 10:57, Roger Pau Monné wrote: > On Sat, Mar 06, 2021 at 09:41:48PM +0000, Julien Grall wrote: >> From: Julien Grall >> >> Compilers older than 4.8 have known codegen issues which can lead to >> silent miscompilation: >> >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 >> >> Furthermore, pre-4.9 GCC have known bugs (including things like >> internal compiler errors on Arm) which would require workaround (I >> haven't checked if we have any in Xen). >> >> The minimum version of GCC to build the hypervisor is now raised to 4.9. > > The README entry doesn't differentiate between tools and hypervisor > GCC version, can the bug above also manifest in toolstack code? I guess it can manifest in the firmware (e.g. hvmloader, rombios). It looks rather unlikely in the userspace tools as we seem to barely use volatile. For the Arm64 bug [1], I think it can also show up when receiving a signal. > > I don't think it makes much sense to have diverging requirements for > tools vs hypervisor builds, but if the bug(s) can also manifest in > toolstack code we might want to add a GCC version check to > tools/configure.ac. Agree. I can add check in ./configure for the toolstack. Cheers, [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293 -- Julien Grall