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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 043E9C433DF for ; Thu, 25 Jun 2020 09:25:25 +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 CBF0C2063A for ; Thu, 25 Jun 2020 09:25:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=xen.org header.i=@xen.org header.b="P8PuKnNF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBF0C2063A 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 localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1joO7o-0007ve-5o; Thu, 25 Jun 2020 09:24:52 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1joO7n-0007vZ-Cg for xen-devel@lists.xenproject.org; Thu, 25 Jun 2020 09:24:51 +0000 X-Inumbo-ID: b86fbe06-b6c5-11ea-818b-12813bfff9fa Received: from mail.xenproject.org (unknown [104.130.215.37]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id b86fbe06-b6c5-11ea-818b-12813bfff9fa; Thu, 25 Jun 2020 09:24:50 +0000 (UTC) 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:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=uT8yp1vueWRxG+AUh0WvEoJgInnLT9zSJamoBslAAjo=; b=P8PuKnNF7A7p9UXvZKI/BUGisq 1FX7DwSJSjkG8tWGu+ox2znjZhRbhF46kkfx+JWEnPPtDaJ4pNDv1ad3ZJqM1YKMoKznP/e9TB1BY LcO1ZHhmDmlrs+rlQKOQy/JLPdkTfbbje7MFS0KtiBcd/GLRNrZp/zplG0vkmndG45pc=; Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1joO7k-0002sm-RQ; Thu, 25 Jun 2020 09:24:48 +0000 Received: from [54.239.6.186] (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 1joO7k-0006rT-KJ; Thu, 25 Jun 2020 09:24:48 +0000 Subject: Re: [PATCH for-4.14] mm: fix public declaration of struct xen_mem_acquire_resource To: Jan Beulich References: <20200623135246.66170-1-roger.pau@citrix.com> <50e25ef7-e7a7-d2c1-5f78-ce32cae35f38@suse.com> <20200623155609.GS735@Air-de-Roger> <20200623172652.GU735@Air-de-Roger> <24d35c4d-e2b3-1f58-4c6e-71072de01b74@suse.com> <04410978-33bf-dedf-7401-248b1a038a9c@xen.org> <60ac0a67-1448-4b39-4489-42dc008b6355@suse.com> From: Julien Grall Message-ID: Date: Thu, 25 Jun 2020 10:24:45 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <60ac0a67-1448-4b39-4489-42dc008b6355@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Wei Liu , paul@xen.org, Andrew Cooper , Ian Jackson , George Dunlap , xen-devel@lists.xenproject.org, =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Hi Jan, On 24/06/2020 15:01, Jan Beulich wrote: > On 24.06.2020 15:41, Julien Grall wrote: >> On 24/06/2020 11:12, Jan Beulich wrote: >>> On 23.06.2020 19:26, Roger Pau Monné wrote: >>>> I'm confused. Couldn't we switch from uint64_aligned_t to plain >>>> uint64_t (like it's currently on the Linux headers), and then use the >>>> compat layer in Xen to handle the size difference when called from >>>> 32bit environments? >>> >>> And which size would we use there? The old or the new one (breaking >>> future or existing callers respectively)? Meanwhile I think that if >>> this indeed needs to not be tools-only (which I still question), >> >> I think we now agreed on a subthread that the kernel needs to know the >> layout of the hypercall. >> >>> then our only possible route is to add explicit padding for the >>> 32-bit case alongside the change you're already making. >> >> AFAICT Linux 32-bit doesn't have this padding. So wouldn't it make >> incompatible the two incompatible? > > In principle yes. But they're putting the structure instance on the > stack, so there's not risk from Xen reading 4 bytes too many. I'd > prefer keeping the interface as is (i.e. with the previously > implicit padding made explicit) to avoid risking to break other > possible callers. But that's just my view on it, anyway ... It makes sense to me. As Roger said, we would also want to update the Linux kernel header for future release. Cheers, -- Julien Grall