From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH 5 of 9] libxl: add libxl_domain_preserve Date: Mon, 26 Jul 2010 16:56:56 +0100 Message-ID: <1280159816.13417.279.camel@localhost.localdomain> References: <85b50d34d7cc8a70c083.1280141809@localhost.localdomain> <19533.43564.160252.987947@mariner.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <19533.43564.160252.987947@mariner.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Ian Jackson Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On Mon, 2010-07-26 at 16:30 +0100, Ian Jackson wrote: > Ian Campbell writes ("[Xen-devel] [PATCH 5 of 9] libxl: add libxl_domain_preserve"): > > This method is intended to preserve an existing domain (for debugging > > purposes) in such a way that the domain can also be restarted. > > This sounds interesting, but I'm not quite sure what the semantics are > intended to be. I guess it works on an existing running domain or a > paused one. Does it stop the domain's execution ? It was intended to be used to implement the rename-restart action for the on_reboot (and on_crash I guess) actions which I introduce in a later patch. I only added this option because xend has it -- I'd be just as happy to only implement simple restart until someone who wants the behaviour comes along. In the meantime preserve or coredump-restart are pretty good substitutes for rename-restart. Anyhow the actual actual semantics of libxl_domain_preserve is that it acts on a shutdown (but not destroyed) domain. The name and/or comments could certainly better reflect this. > The current code seems mainly to change the name and the uuid in > xenstore - to a specified new uuid - which seems a strange thing to > do. It's (a subset of) what xend does ;-) (For reference its XendDomainInfo._preserveForRestart from tools/python/xen/xend/XendDomainInfo.py) I suspect the reason is something to do with not nuking /vm/ for a running domain when destroying a previously preserved instance of that domain. Ian.