From mboxrd@z Thu Jan 1 00:00:00 1970 From: Derrik Pates Subject: Re: Xen newbie: inter-domain communication Date: Fri, 07 Jan 2005 21:59:27 -0500 Message-ID: <41DF4C8F.8020107@dsdk12.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Chotu Ram Cc: xen-devel@lists.sourceforge.net List-Id: xen-devel@lists.xenproject.org Chotu Ram wrote: > 1. As far as I can understand (and I might be wrong) Xen maintains two > domains dom0 (control domain) and dom1 (the other guest OSes). When the > documentation says inter-domain communication, is it only referring to > the communication between the dom0 and dom1, or it can also be applied > to the communication among the guest OSes (unprivileged that is). A "domain" is a single virtual execution space, more or less. Each "virtual machine" is a separate domain. (When you do "xm list", the "Id" field is the "domain ID".) So yes, an inter-domain commmunication channel can exist between domain 0 and any other domain (running virtual machine). > 2. What are the capabilities of the inter-domain communication method. > Specifically: what protocol is used to communicate?, what kind of > information can be communicated? Can this communication be used for > logging/auditing? Does anybody has any experience using this method or > has any working example? As I understand, the "protocol" is basically just a per-channel "interrupt" (to get the other side's attention as needed), and a shared page, which is exchanged between the two domains as needed (only one can be interacting with it at a time, I think). The virtual block device driver and virtual network interface driver, as I understand it, structure it as a big ring buffer, and encode messages (and assign pages of their allocated memory to the other side of the channel for a DMA-like exchange method) in that ring buffer. Look at the developer documentation for a better explanation. -- Derrik Pates dpates@dsdk12.net ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt