From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964988AbXCODJb (ORCPT ); Wed, 14 Mar 2007 23:09:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965013AbXCODJb (ORCPT ); Wed, 14 Mar 2007 23:09:31 -0400 Received: from pop-siberian.atl.sa.earthlink.net ([207.69.195.71]:61333 "EHLO pop-siberian.atl.sa.earthlink.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964988AbXCODJa (ORCPT ); Wed, 14 Mar 2007 23:09:30 -0400 Subject: Re: [kvm-devel] [PATCH 01/15] KVM: Use a shared page for kernel/user communication when runing a vcpu From: Hollis Blanchard To: Avi Kivity Cc: kvm-devel@lists.sourceforge.net, Andrew Morton , linux-kernel@vger.kernel.org In-Reply-To: <1173926306.4611.6.camel@diesel> References: <11736212072915-git-send-email-avi@qumranet.com> <1173621207773-git-send-email-avi@qumranet.com> <1173926306.4611.6.camel@diesel> Content-Type: text/plain Date: Wed, 14 Mar 2007 22:09:23 -0500 Message-Id: <1173928163.4611.13.camel@diesel> Mime-Version: 1.0 X-Mailer: Evolution 2.8.3 (2.8.3-1.fc6) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-03-14 at 21:38 -0500, Hollis Blanchard wrote: > On Sun, 2007-03-11 at 15:53 +0200, Avi Kivity wrote: > > Instead of passing a 'struct kvm_run' back and forth between the > > kernel and userspace, allocate a page and allow the user to mmap() it. > > This reduces needless copying and makes the interface expandable by > > providing lots of free space. > > Do you provide for another means of accessing guest memory from host > userspace? For example, how do you attach a host debugger to the guest? > > Xen uses an ioctl followed by mmap for this purpose, which is why I > wonder about using mmap(/dev/kvm) for another purpose. Never mind: I see now that you have separate device nodes for the VM vs each vcpu. -Hollis