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=-2.2 required=3.0 tests=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 52CC2C54FCC for ; Mon, 20 Apr 2020 08:05:04 +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 26ED6218AC for ; Mon, 20 Apr 2020 08:05:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 26ED6218AC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com 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 4.89) (envelope-from ) id 1jQRQ4-0004fP-QR; Mon, 20 Apr 2020 08:04:44 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jQRQ3-0004fG-Dh for xen-devel@lists.xenproject.org; Mon, 20 Apr 2020 08:04:43 +0000 X-Inumbo-ID: 96e65fcc-82dd-11ea-9e09-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 96e65fcc-82dd-11ea-9e09-bc764e2007e4; Mon, 20 Apr 2020 08:04:42 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 82B1AAFB4; Mon, 20 Apr 2020 08:04:40 +0000 (UTC) Subject: Re: [PATCH] pvcalls: Document explicitly the padding for all arches To: Julien Grall References: <20200419104948.31200-1-julien@xen.org> From: Jan Beulich Message-ID: Date: Mon, 20 Apr 2020 10:04:39 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200419104948.31200-1-julien@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Wei Liu , Andrew Cooper , Julien Grall , Ian Jackson , George Dunlap , xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 19.04.2020 12:49, Julien Grall wrote: > --- a/docs/misc/pvcalls.pandoc > +++ b/docs/misc/pvcalls.pandoc > @@ -246,9 +246,7 @@ The format is defined as follows: > uint32_t domain; > uint32_t type; > uint32_t protocol; > - #ifdef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > } socket; > struct xen_pvcalls_connect { > uint64_t id; > @@ -257,16 +255,12 @@ The format is defined as follows: > uint32_t flags; > grant_ref_t ref; > uint32_t evtchn; > - #ifdef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > } connect; > struct xen_pvcalls_release { > uint64_t id; > uint8_t reuse; > - #ifdef CONFIG_X86_32 > uint8_t pad[7]; > - #endif > } release; > struct xen_pvcalls_bind { > uint64_t id; > @@ -276,9 +270,7 @@ The format is defined as follows: > struct xen_pvcalls_listen { > uint64_t id; > uint32_t backlog; > - #ifdef CONFIG_X86_32 > uint8_t pad[4]; > - #endif > } listen; > struct xen_pvcalls_accept { > uint64_t id; I wonder on what grounds these #ifdef-s had been there - they're plain wrong with the types used in the public header. > --- a/xen/include/public/io/pvcalls.h > +++ b/xen/include/public/io/pvcalls.h > @@ -65,6 +65,7 @@ struct xen_pvcalls_request { > uint32_t domain; > uint32_t type; > uint32_t protocol; > + uint8_t pad[4]; > } socket; > struct xen_pvcalls_connect { > uint64_t id; > @@ -73,10 +74,12 @@ struct xen_pvcalls_request { > uint32_t flags; > grant_ref_t ref; > uint32_t evtchn; > + uint8_t pad[4]; > } connect; > struct xen_pvcalls_release { > uint64_t id; > uint8_t reuse; > + uint8_t pad[7]; > } release; > struct xen_pvcalls_bind { > uint64_t id; > @@ -86,6 +89,7 @@ struct xen_pvcalls_request { > struct xen_pvcalls_listen { > uint64_t id; > uint32_t backlog; > + uint8_t pad[4]; > } listen; I'm afraid we can't change these in such a way - your additions change sizeof() for the respective sub-structures on 32-bit x86, and hence this is not a backwards compatible adjustment. The best I can think of right now that we could do is make the difference explicit, by putting the padding fields inside #ifndef __i386__. But of course this is awkward at least when thinking about a 32-bit / 64-bit pair of communication ends on an x86-64 host. Jan