From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: [Qemu-devel] Using PCI config space to indicate config location Date: Wed, 10 Oct 2012 14:14:47 +1030 Message-ID: <87txu36le8.fsf@rustcorp.com.au> References: <874nmajcmj.fsf@codemonkey.ws> <87y5jhpuu2.fsf@rustcorp.com.au> <87bogddq0l.fsf@codemonkey.ws> <5072EA14.30809@redhat.com> <87k3v1gfw1.fsf@codemonkey.ws> <507333F1.1060000@redhat.com> <874nm4u1in.fsf@codemonkey.ws> <87sj9o8qn7.fsf@rustcorp.com.au> <87sj9oh0pm.fsf@codemonkey.ws> <87haq48hds.fsf@rustcorp.com.au> <20121009210901.GY14867@jl-vm1.vm.bytemark.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , kvm@vger.kernel.org, "Michael S. Tsirkin" , qemu-devel , virtualization@lists.linux-foundation.org To: Jamie Lokier Return-path: In-Reply-To: <20121009210901.GY14867@jl-vm1.vm.bytemark.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: kvm.vger.kernel.org Jamie Lokier writes: > Rusty Russell wrote: >> I don't think it'll be that bad; reset clears the device to unknown, >> bar0 moves it from unknown->legacy mode, bar1/2/3 changes it from >> unknown->modern mode, and anything else is bad (I prefer being strict so >> we catch bad implementations from the beginning). > > Will that work, if the guest with kernel that uses modern mode, kexecs > to an older (but presumed reliable) kernel that only knows about legacy mode? > > I.e. will the replacement kernel, or (ideally) replacement driver on > the rare occasion that is needed on a running kernel, be able to reset > the device hard enough? Well, you need to reset the device, so yes. Cheers, Rusty.