From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH RFC] virtio-pci: new config layout: using memory BAR Date: Wed, 05 Jun 2013 07:59:33 -0500 Message-ID: <871u8g67d6.fsf@codemonkey.ws> References: <20130528160342.GA29915@redhat.com> <87bo7vvxej.fsf@codemonkey.ws> <87ppwammp5.fsf@rustcorp.com.au> <87mwreq76y.fsf@codemonkey.ws> <87wqqhktjx.fsf@rustcorp.com.au> <87fvx460ba.fsf@codemonkey.ws> <20130530140132.GC21440@redhat.com> <874ndgujiw.fsf@rustcorp.com.au> <20130603101136.GB8649@redhat.com> <87fvwytpa1.fsf@rustcorp.com.au> <20130604064216.GD19433@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130604064216.GD19433@redhat.com> 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 To: "Michael S. Tsirkin" , Rusty Russell Cc: Peter Maydell , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Stefan Hajnoczi , Paolo Bonzini , KONRAD Frederic List-Id: virtualization@lists.linuxfoundation.org "Michael S. Tsirkin" writes: > On Tue, Jun 04, 2013 at 03:01:50PM +0930, Rusty Russell wrote: > You mean make BAR0 an MMIO BAR? > Yes, it would break current windows guests. > Further, as long as we use same address to notify all queues, > we would also need to decode the instruction on x86 and that's > measureably slower than PIO. > We could go back to discussing hypercall use for notifications, > but that has its own set of issues... So... does "violating the PCI-e" spec really matter? Is it preventing any guest from working properly? I don't think we should rush an ABI breakage if the only benefit is claiming spec compliance. Regards, Anthony Liguori > > -- > MST > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html