From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCHv3] virtio-spec: 64 bit features, used/avail event, fixes Date: Wed, 3 Aug 2011 19:39:23 +0300 Message-ID: <20110803163923.GA17244@redhat.com> References: <20110601102548.GA11013@redhat.com> <87ei3dxas0.fsf@rustcorp.com.au> <20110803160518.GA16563@redhat.com> <4E397425.90808@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rusty Russell , virtualization@lists.linux-foundation.org, habanero@linux.vnet.ibm.com, Shirley Ma , Krishna Kumar2 , kvm@vger.kernel.org, steved@us.ibm.com, Tom Lendacky , borntraeger@de.ibm.com, avi@redhat.com, bryanv@daemoninthecloset.org To: Gerd Hoffmann Return-path: Received: from mx1.redhat.com ([209.132.183.28]:15855 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752532Ab1HCQjt (ORCPT ); Wed, 3 Aug 2011 12:39:49 -0400 Content-Disposition: inline In-Reply-To: <4E397425.90808@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Aug 03, 2011 at 06:15:33PM +0200, Gerd Hoffmann wrote: > Hi, > > >E.g. with 32 bridges, and 32 devices behind each one, > >the available 64K space gets us only 64 bytes per device. > > 15 bridges (with io window enabled) max, the smallest io window you > can assign to a bridge is 4k, and you need some space for the > devices on the root bus ... > > cheers, > Gerd Hmm, wait, we could go 32 bit, then we are not limited to 32 bridges anymore, right? Does our bios support that? -- MST