From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 12/22] virtio_pci: allow duplicate capabilities. Date: Thu, 21 Mar 2013 20:01:26 +0200 Message-ID: <20130321180126.GA4366@redhat.com> References: <514B2FA0.9000204@zytor.com> <20130321161143.GC1925@redhat.com> <514B3213.8070002@zytor.com> <20130321162636.GF1925@redhat.com> <514B3606.2090503@zytor.com> <20130321170706.GB2994@redhat.com> <514B3EAE.8000707@zytor.com> <20130321171319.GD2994@redhat.com> <20130321174912.GA4161@redhat.com> <514B4957.1070003@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <514B4957.1070003@zytor.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: "H. Peter Anvin" Cc: virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Thu, Mar 21, 2013 at 10:54:31AM -0700, H. Peter Anvin wrote: > On 03/21/2013 10:49 AM, Michael S. Tsirkin wrote: > > > > Just to clarify, I expect BIOS to use it *for config access*. > > Notification will support IO anyway because it's > > faster on KVM, so BIOS can use it directly. > > > > Ah, yes, of course. > > Quite frankly, I don't see any reason to support *anything else* for > configuration, does anyone else? > > I thought we were talking about the doorbell/notification/kicker > register. For I/O space especially it is highly desirable if that can > be in a minimal BAR (4 bytes). > > -hpa Not necessarily a BAR. We have trouble allocating IO BARs. What I want to allow is hypervisor which allocates a fixed address/data pair in the hypervisor, reserves it in ACPI and reports to driver through a vendor specific capability. You likely didn't see this discussion, it was only sent to kvm and virtualization lists, the subject is 'virtio PCI on KVM without IO BARs' -- MST