From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: preview of in kernel irqchip live migration support Date: Wed, 25 Jul 2007 10:30:48 +0300 Message-ID: <46A6FC28.6010207@qumranet.com> References: <10EA09EFD8728347A513008B6B0DA77A01D15BAB@pdsmsx411.ccr.corp.intel.com> <64F9B87B6B770947A9F8391472E032160CD8CAD6@ehost011-8.exch011.intermedia.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Dor Laor Return-path: In-Reply-To: <64F9B87B6B770947A9F8391472E032160CD8CAD6-yEcIvxbTEBqsx+V+t5oei8rau4O3wl8o3fe8/T/H7NteoWH0uzbU5w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Dor Laor wrote: >> This patch is only for idea collection so far. >> The dilemma is that how to export the pic/IOAPIC/apic state data >> structure to user and make sure it has same/similar structure in user >> level. >> Otherwise a >> convert is a must and we must maintain the converter. >> > > IMHO there is no need of supporting migration from/to kernel/user. > The main point of maintaining pic/apic/ioapic in to test our > implementation against > a stable working implementation. Once the kernel implementation will be > stable > there is no need to support the userspace. > > No, we have to support 2.6.22 and 2.6.23 which don't have in-kernel apic. We need to avoid multiple migration (and state save) formats. > >> With this, PIC only guest can do live migration successfully. We can >> extend APIC side seamlessly. >> >> BTW, there is potential issue in IDT_Vectoring. The fix IMO is to retry >> vm_stop at user level to make sure no pending IDT_vectoring. >> > > Isn't it possible to serialize the pending IDT_vectoring too? > If the answer is no, the solution is to add an ioctl that will test the > pending > statis in migration.c::migrate_check_convergence. If it's pending, add > another > migrate_write loop iteration. > IDT_vectoring is am implementation detail, we don't want to expose it in the migration protocol because it ties us up. Best to avoid it. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/