From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH RFC] virtio-pci: add MMIO property Date: Mon, 19 Mar 2012 19:58:12 +0200 Message-ID: <4F6773B4.2040209@redhat.com> References: <20120319155650.GA6430@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120319155650.GA6430@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" Cc: Anthony Liguori , kvm@vger.kernel.org, Alexey Kardashevskiy , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On 03/19/2012 05:56 PM, Michael S. Tsirkin wrote: > Currently virtio-pci is specified so that configuration of the device is > done through a PCI IO space (via BAR 0 of the virtual PCI device). > However, Linux guests happen to use ioread/iowrite/iomap primitives > for access, and these work uniformly across memory/io BARs. > > While PCI IO accesses are faster than MMIO on x86 kvm, > MMIO might be helpful on other systems which don't > implement PIO or where PIO is slower than MMIO. > > Add a property to make it possible to tweak the BAR type. > > Signed-off-by: Michael S. Tsirkin > > This is harmless by default but causes segfaults in memory.c > when enabled. Thus an RFC until I figure out what's wrong. > Should be done via an extra BAR (with the same layout, perhaps extended) so compatibility is preserved. -- error compiling committee.c: too many arguments to function