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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 C0B63C4332D for ; Thu, 11 Mar 2021 08:18:16 +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 4C78964F4D for ; Thu, 11 Mar 2021 08:18:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C78964F4D Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com 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.96383.182258 (Exim 4.92) (envelope-from ) id 1lKGWA-0006ak-E8; Thu, 11 Mar 2021 08:18:02 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 96383.182258; Thu, 11 Mar 2021 08:18:02 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKGWA-0006ad-Ax; Thu, 11 Mar 2021 08:18:02 +0000 Received: by outflank-mailman (input) for mailman id 96383; Thu, 11 Mar 2021 08:18:00 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKGW8-0006aW-Hq for xen-devel@lists.xenproject.org; Thu, 11 Mar 2021 08:18:00 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 5c311390-9ac6-4011-bb0f-bfbed8b020d6; Thu, 11 Mar 2021 08:17:59 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A435CAC16; Thu, 11 Mar 2021 08:17:58 +0000 (UTC) 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" X-Inumbo-ID: 5c311390-9ac6-4011-bb0f-bfbed8b020d6 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1615450678; h=from:from:reply-to: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=bpixSMGVIw+5F7WyNe2N5wSzzZOriV1Vf/ISr/6LqTA=; b=Uh265zkSW0W9nFgml3FrvU8/LzBZSEQzCAwzm8poZs0KrDQyarRjMRdmLdNIpSqV6FDGCr it4YlNL9CV6wx8pSuYrzD/aQxj8cxUW4FmOeOiF/E2y6p9msw9XKQMKTlWVAxCjKBljWSX iaLl+3lQU6vs/IQ0Kz7sTO36QfS5/6E= Subject: Re: [PATCH for-4.15] xen: Bump the minimum version of GCC supported to 4.9 (5.1 on arm64) To: Julien Grall Cc: Julien Grall , Andrew Cooper , George Dunlap , Ian Jackson , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20210306214148.27021-1-julien@xen.org> <1897022d-7591-3450-4e57-884a2860b13d@suse.com> <7fd07dc9-9c03-bb13-3907-c3c268a4e970@xen.org> <2de5160f-8636-5cdf-a20c-acaa2640c893@suse.com> <7ab87cab-8836-e8a0-993e-0cdeca3c45e3@xen.org> From: Jan Beulich Message-ID: <2bc2ad13-8636-e5d4-3a4a-722c75e3b92a@suse.com> Date: Thu, 11 Mar 2021 09:17:58 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <7ab87cab-8836-e8a0-993e-0cdeca3c45e3@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 10.03.2021 19:05, Julien Grall wrote: > On 09/03/2021 11:20, Jan Beulich wrote: >> On 08.03.2021 21:22, Julien Grall wrote: >>> On 08/03/2021 11:20, Jan Beulich wrote: >>>> On 08.03.2021 11:51, Julien Grall wrote: >>>>> On 08/03/2021 08:09, Jan Beulich wrote: >>>>>> Additionally - partly related to your own reply regarding the CI >>>>>> failures - imo there needs to be an analysis of what older distros >>>>>> will no longer build (at all or by default). >>>>> >>>>> Per the CI, this would be Ubuntu Trusty (and older), Centos 7 (and older) >>>>> >>>>> Do you have any other in mind? >>>> >>>> Our SLE12 (latest service pack is SP5 and still has a while to go >>>> to at least reach LTSS state) comes with gcc 4.8 as the default >>>> compiler. >>> >>> Thanks! That's good to know. Is it the old GCC Suse supports? >> >> Not sure I understand the question: The default compiler of this or >> any distro is of course (expected to be) supported by the vendor >> for the lifetime of the OS. > > Sorry for the wording. I was asking whether Suse also supports compiler > older than GCC 4.8. Oh, I see. SLES11 has another year to go for LTSS to end, and it's 4.3 which is used there. >>>>>>> --- a/xen/include/xen/compiler.h >>>>>>> +++ b/xen/include/xen/compiler.h >>>>>>> @@ -5,6 +5,19 @@ >>>>>>> #error Sorry, your compiler is too old/not recognized. >>>>>>> #endif >>>>>>> >>>>>>> +#if CONFIG_CC_IS_GCC >>>>>>> +# if CONFIG_GCC_VERSION < 40900 >>>>>>> +/* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 */ >>>>>> >>>>>> As per the bug report, the issue was determined to not be present >>>>>> in e.g. 4.3. Hence while such a bug may influence our choice of >>>>>> minimum version, I don't think it can reasonably be named here as >>>>>> the apparent only reason for the choice. Personally I don't think >>>>>> any justification should be put here. >>>>> >>>>> Ok. >>>>> >>>>>> >>>>>>> +# error Sorry, your version of GCC is too old - please use 4.9 or newer. >>>>>>> +# elif defined(CONFIG_ARM_64) && CONFIG_GCC_VERSION < 50100 >>>>>>> +/* >>>>>>> + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293 >>>>>>> + * https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk >>>>>>> + */ >>>>>>> +# error Sorry, your version of GCC is too old - please use 5.1 or newer. >>>>>> >>>>>> From the bug entry the fix looks to have been backported to 4.9, >>>>>> or at least some (important?) branches thereof. >>>>> >>>>> It is not clear what's you are trying to point out. Mind clarifying? >>>> >>>> Some 4.9 compilers (perhaps widely used ones) may not have the bad >>>> issue, which puts under question their ruling out when the main >>>> reason for doing so is that bug. >>> >>> Well... We could surely try to hunt which GCC 4.9 has been fixed. But I >>> am not convinced this is useful, we would need to have an allowlist of >>> GCC compiler. >> >> Or probe the compiler for the bug in question. > > I thought about it but it is not clear to me whether the reproducer > would work on every GCC version and how to detect that this was miscompiled. > > Do you have any suggestion? To have one I'd have to study the problem in quite a bit more detail. But I did say that what you do for Arm is largely up to you (and Stefano did meanwhile ack the Arm side), so I'm not sure I want to invest the time that would be needed. Jan