From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753291AbbINAhT (ORCPT ); Sun, 13 Sep 2015 20:37:19 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:19677 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752143AbbINAhS (ORCPT ); Sun, 13 Sep 2015 20:37:18 -0400 Message-ID: <55F616B2.2070703@oracle.com> Date: Mon, 14 Sep 2015 08:37:06 +0800 From: Bob Liu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Julien Grall CC: xen-devel@lists.xenproject.org, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, linux-kernel@vger.kernel.org, David Vrabel , Boris Ostrovsky , =?UTF-8?B?Um9nZXIgUGF1IE1v?= =?UTF-8?B?bm7DqQ==?= Subject: Re: [Xen-devel] [PATCH 0/2] block/xen-blkfront: Support non-indirect with 64KB page granularity References: <1441999920-3639-1-git-send-email-julien.grall@citrix.com> <55F3F460.7000702@oracle.com> <55F566DC.7080804@citrix.com> <55F56FC7.4050600@oracle.com> <55F5B6BD.4030904@citrix.com> In-Reply-To: <55F5B6BD.4030904@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/14/2015 01:47 AM, Julien Grall wrote: > > > On 13/09/2015 13:44, Bob Liu wrote: >> I may misunderstood here. >> But I think same changes are also required even if backend supports indirect grant when frontend is using 64KB page granularity. >> Else >> 1) How to set up the grant map for requests in domU? >> The minimum segment buffer size in a request is PAGE_SIZE(64KB) while grant is 4KB based. >> >> 2) Codes like below in blkback.c may not work correctly? >> if ((req->u.rw.seg[i].last_sect >= (PAGE_SIZE >> 9)) || >> >> Because PAGE_SIZE in backend is 4KB, while the written value by domU is 64KB based. > > As mention in my cover letter, this patch is not self-sufficient to support 64KB guest. It's a follow-up of the 64KB page granularity support I sent on the ML (the new version was sent earlier this week [1]). > > One of the patch [2] is taking care of breaking down the I/O request in multiple 4KB segment that will be used in the ring request. You may want to give a look to this patch before looking to this series. > Oh, sorry! I'll have a look at those patches. Thanks, -Bob