From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH 28/35] kvm: x86: Introduce kvmclock device to save/restore its state Date: Wed, 19 Jan 2011 10:57:11 -0600 Message-ID: <4D3717E7.3010105@linux.vnet.ibm.com> References: <4D2B6CB5.9050602@codemonkey.ws> <4D2B74D8.4080309@web.de> <4D2B8662.9060909@web.de> <4D2C60FB.7030009@linux.vnet.ibm.com> <4D2D80ED.8030405@redhat.com> <4D2D82EE.20002@siemens.com> <4D35A39A.8000801@siemens.com> <4D35ABF8.9050700@linux.vnet.ibm.com> <4D35B521.3090601@siemens.com> <4D35B6DD.1020005@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , Jan Kiszka , Glauber Costa , Marcelo Tosatti , "qemu-devel@nongnu.org" , Avi Kivity To: Markus Armbruster Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On 01/19/2011 07:15 AM, Markus Armbruster wrote: > So they interact with KVM (need kvm_state), and they interact with the > emulated PCI bus. Could you elaborate on the fundamental difference > between the two interactions that makes you choose the (hypothetical) > KVM bus over the PCI bus as device parent? > It's almost arbitrary, but I would say it's the direction that I/Os flow. But if the underlying observation is that the device tree is not really a tree, you're 100% correct. This is part of why a factory interface that just takes a parent bus is too simplistic. I think we ought to introduce a -pci-device option that is specifically for creating PCI devices that doesn't require a parent bus argument but provides a way to specify stable addressing (for instancing, using a linear index). Regards, Anthony Liguori From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=45449 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PfbLd-00044s-0g for qemu-devel@nongnu.org; Wed, 19 Jan 2011 11:57:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PfbLb-0007hf-MI for qemu-devel@nongnu.org; Wed, 19 Jan 2011 11:57:28 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:34397) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PfbLb-0007hP-Gx for qemu-devel@nongnu.org; Wed, 19 Jan 2011 11:57:27 -0500 Received: from d03relay03.boulder.ibm.com (d03relay03.boulder.ibm.com [9.17.195.228]) by e31.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id p0JGh7QT003377 for ; Wed, 19 Jan 2011 09:43:07 -0700 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay03.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p0JGvNIs109306 for ; Wed, 19 Jan 2011 09:57:24 -0700 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p0JGvN1D000312 for ; Wed, 19 Jan 2011 09:57:23 -0700 Message-ID: <4D3717E7.3010105@linux.vnet.ibm.com> Date: Wed, 19 Jan 2011 10:57:11 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH 28/35] kvm: x86: Introduce kvmclock device to save/restore its state References: <4D2B6CB5.9050602@codemonkey.ws> <4D2B74D8.4080309@web.de> <4D2B8662.9060909@web.de> <4D2C60FB.7030009@linux.vnet.ibm.com> <4D2D80ED.8030405@redhat.com> <4D2D82EE.20002@siemens.com> <4D35A39A.8000801@siemens.com> <4D35ABF8.9050700@linux.vnet.ibm.com> <4D35B521.3090601@siemens.com> <4D35B6DD.1020005@linux.vnet.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: "kvm@vger.kernel.org" , Jan Kiszka , Glauber Costa , Marcelo Tosatti , "qemu-devel@nongnu.org" , Avi Kivity On 01/19/2011 07:15 AM, Markus Armbruster wrote: > So they interact with KVM (need kvm_state), and they interact with the > emulated PCI bus. Could you elaborate on the fundamental difference > between the two interactions that makes you choose the (hypothetical) > KVM bus over the PCI bus as device parent? > It's almost arbitrary, but I would say it's the direction that I/Os flow. But if the underlying observation is that the device tree is not really a tree, you're 100% correct. This is part of why a factory interface that just takes a parent bus is too simplistic. I think we ought to introduce a -pci-device option that is specifically for creating PCI devices that doesn't require a parent bus argument but provides a way to specify stable addressing (for instancing, using a linear index). Regards, Anthony Liguori