From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yang Hongyang Subject: Re: [PATCH v3 COLOPre 19/26] libxc/migration: Specification update for DIRTY_BITMAP records Date: Wed, 1 Jul 2015 11:07:05 +0800 Message-ID: <55935959.3050606@cn.fujitsu.com> References: <1435213552-10556-1-git-send-email-yanghy@cn.fujitsu.com> <1435213552-10556-20-git-send-email-yanghy@cn.fujitsu.com> <1435659898.21469.79.camel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1435659898.21469.79.camel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: wei.liu2@citrix.com, wency@cn.fujitsu.com, andrew.cooper3@citrix.com, yunhong.jiang@intel.com, eddie.dong@intel.com, xen-devel@lists.xen.org, guijianfeng@cn.fujitsu.com, rshriram@cs.ubc.ca, ian.jackson@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On 06/30/2015 06:24 PM, Ian Campbell wrote: > On Thu, 2015-06-25 at 14:25 +0800, Yang Hongyang wrote: >> Used by secondary to send it's dirty bitmap to primary under COLO. > > This is the backchannel, right? Right. > > It seems to me that this ought to be described more clearly as a > separate stream in the opposite direction, rather than looking like just > another record in the forward channel. Agreed, I'm not sure if having this back channel record is eligible, Andy, thoughts? > > Does the back channel not also need some sort of negotiation phase where > we check both ends are compatible (i.e. like the forward channel's > header). This might be easier than with the forward channel since you > might assert that the versions must match exactly for COLO to be > possible, that might not be true of some potential future user of the > backchannel though. The negotiation record for COLO is introduced in the following patch on libxl side. But that might be diffrent form what you said here, we don't have a version check currently, if the 2 side doesn't match, for example one has colo feature enabled and the other end do not, the migration will simply fail. > > > . > -- Thanks, Yang.