From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: How to detect HAP from DomU? Date: Wed, 10 Nov 2010 09:22:50 +0100 Message-ID: <4CDA565A.5040804@ts.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org Hi, is there any way for a HVM-domain to detect whether it is running with HAP enabled? I couldn't find any interface for this information. Background: in our BS2000 domain (HVM with PV-drivers) we sometimes have to copy complete pages between kernel and user. An alternative to the copy would be a remapping of the page. The remap is faster than the copy with HAP enabled, but much slower without HAP. So it would be best to copy without HAP and remap with HAP. I think this would be a candidate for XEN features (another bit in xen/include/public/features.h). If there are no objections to this idea, I'll make a patch. Juergen -- Juergen Gross Principal Developer Operating Systems TSP ES&S SWE OS6 Telephone: +49 (0) 89 3222 2967 Fujitsu Technology Solutions e-mail: juergen.gross@ts.fujitsu.com Domagkstr. 28 Internet: ts.fujitsu.com D-80807 Muenchen Company details: ts.fujitsu.com/imprint.html