From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36230) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsZNm-0006DT-34 for qemu-devel@nongnu.org; Fri, 28 Jun 2013 10:10:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UsZNf-0007B2-Ip for qemu-devel@nongnu.org; Fri, 28 Jun 2013 10:10:38 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:38541) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsZNf-0007Av-Ds for qemu-devel@nongnu.org; Fri, 28 Jun 2013 10:10:31 -0400 Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 28 Jun 2013 10:10:30 -0400 Received: from d01relay03.pok.ibm.com (d01relay03.pok.ibm.com [9.56.227.235]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id CC58AC9003E for ; Fri, 28 Jun 2013 10:10:27 -0400 (EDT) Received: from d01av05.pok.ibm.com (d01av05.pok.ibm.com [9.56.224.195]) by d01relay03.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5SEASNU299344 for ; Fri, 28 Jun 2013 10:10:28 -0400 Received: from d01av05.pok.ibm.com (loopback [127.0.0.1]) by d01av05.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5SE0cmQ029857 for ; Fri, 28 Jun 2013 10:00:39 -0400 Message-ID: <51CD9706.1000804@linux.vnet.ibm.com> Date: Fri, 28 Jun 2013 10:00:38 -0400 From: "Michael R. Hines" MIME-Version: 1.0 References: <1372373098-5877-1-git-send-email-mrhines@linux.vnet.ibm.com> <1372373098-5877-4-git-send-email-mrhines@linux.vnet.ibm.com> <51CD8E44.2090201@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/6] rdma: core logic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: aliguori@us.ibm.com, quintela@redhat.com, qemu-devel@nongnu.org, owasserm@redhat.com, abali@us.ibm.com, mrhines@us.ibm.com, gokul@us.ibm.com, pbonzini@redhat.com, chegu_vinod@hp.com, knoel@redhat.com On 06/28/2013 09:28 AM, Peter Maydell wrote: > On 28 June 2013 14:23, Michael R. Hines wrote: >>> I assume from the PACKED annotations (do we really need both, >>> incidentally) that this is shared with either the guest or >>> with another instance of QEMU. Are there definitely no >>> endianness issues to deal with here? >> >> I have ntohl()/htonl() on the protocol headers, but I did not >> add them for the data portions of the protocol. >> >> >> Is endianess for the data a big issue when you are assume the migration >> is happening across identical CPU architectures? > Well: > * is that a reasonable assumption? (why?) I would yes, because we're dealing raw guest RAM. Migration of memory would not work across a different architecture (particularly page tables - which would need to be canonicalized and de-canonicalized). > * if you try this on some setup where it's not true, do we > fail helpfully or obscurely? Shouldn't a check like that occur before the migration actually begins? Is this specific to RDMA?