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=-5.8 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 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 9904BC433E0 for ; Fri, 12 Mar 2021 10:29:44 +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 5014665004 for ; Fri, 12 Mar 2021 10:29:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5014665004 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=xenproject.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.96975.183990 (Exim 4.92) (envelope-from ) id 1lKf31-0007oL-US; Fri, 12 Mar 2021 10:29:35 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 96975.183990; Fri, 12 Mar 2021 10:29:35 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKf31-0007oE-P2; Fri, 12 Mar 2021 10:29:35 +0000 Received: by outflank-mailman (input) for mailman id 96975; Fri, 12 Mar 2021 10:29:34 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKf30-0007o6-Mt for xen-devel@lists.xenproject.org; Fri, 12 Mar 2021 10:29:34 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lKf30-0005bx-Jd for xen-devel@lists.xenproject.org; Fri, 12 Mar 2021 10:29:34 +0000 Received: from iwj (helo=mariner.uk.xensource.com) by xenbits.xenproject.org with local-bsmtp (Exim 4.92) (envelope-from ) id 1lKf30-00037i-Ik for xen-devel@lists.xenproject.org; Fri, 12 Mar 2021 10:29:34 +0000 Received: from iwj by mariner.uk.xensource.com with local (Exim 4.89) (envelope-from ) id 1lKf2p-0003Z1-Ah; Fri, 12 Mar 2021 10:29:23 +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=xenproject.org; s=20200302mail; h=References:In-Reply-To:Subject:Cc:To:Date :Message-ID:Content-Transfer-Encoding:Content-Type:MIME-Version:From; bh=yGdcISLXILgnM+oQAr1inXBMzVkxhIog+rnf0NeWGWo=; b=WV/14NNTfrMAQ34OURccVv3wn5 3ZfBYIIVKplbeUiWOb7XNJzS/Lhn0zrRipl86RmdEE43Ig/9kmX4i0AuarwRWFtCC6qixjW49f7gz GydeVms6IQMHII4BlwcsjdKyqANI87SqC+EmzY5L9EhhArzJTByHwS63rANKIxMcXcq4=; From: Ian Jackson MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <24651.17027.10811.145589@mariner.uk.xensource.com> Date: Fri, 12 Mar 2021 10:29:23 +0000 To: Jan Beulich Cc: Julien Grall , Andrew Cooper , George Dunlap , Stefano Stabellini , Wei Liu , "xen-devel\@lists.xenproject.org" Subject: Re: [PATCH][4.15] gnttab: work around "may be used uninitialized" warning In-Reply-To: <7185c052-3e66-6202-f820-76568b2b1228@suse.com> References: <6bd14438-7dec-2176-eab5-5898f190c4d8@suse.com> <24651.15544.142804.468744@mariner.uk.xensource.com> <7185c052-3e66-6202-f820-76568b2b1228@suse.com> X-Mailer: VM 8.2.0b under 24.5.1 (i686-pc-linux-gnu) Jan Beulich writes ("Re: [PATCH][4.15] gnttab: work around "may be used uninitialized" warning"): > On 12.03.2021 11:04, Ian Jackson wrote: > > Julien Grall writes ("Re: [PATCH][4.15] gnttab: work around "may be used uninitialized" warning"): > >> This is pretty much what we are already doing slowly by initializing > >> values to shut up older compilers. I agree this is more limited, but we > >> also waive off diagnostics from every single compiler in that code > >> rather than just one version. > >> > >> Hence why I suggested dropping -Werror for older compiler. This is not > >> ideal but it would give us the ability to keep support for dinausor > >> compiler and not hamper our ability to take advantage of newer compiler > >> diagnostics. > > > > I agree with Julien. I think we should avoid adding these redundant > > initialisers for the reasons he gives. > > I find this odd, not only because it is contrary to what we've done so > far. What if more modern gcc issues a false-positive warning? If we'd > fix it there, where would you suggest to draw the line? Imo our tree > should build without issues on all compiler versions which we state we > permit to be used. > > Of course in the case here I could add a "default:" to the switch(), > but this would still only work around the compiler issue. Would the > two of you consider this any better? > > Also, Ian - do you have any alternative suggestion towards making the > build work again (in the more general case, i.e. irrespective of the > alternative suggestion for this specific case just above)? Not using > -Werror on old compilers (again - where would we draw the line) was > already objected to by me. I read your objection to not using -Werror for such old compilers but I did not agree with it. I am sympathetic to Julien's desire to try to limit the set of supported compilers. Ian.