From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48525) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT82f-00055M-DG for qemu-devel@nongnu.org; Wed, 04 Mar 2015 07:04:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YT82W-0004Fm-Nd for qemu-devel@nongnu.org; Wed, 04 Mar 2015 07:04:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57433) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT82W-0004FY-Fh for qemu-devel@nongnu.org; Wed, 04 Mar 2015 07:04:36 -0500 Date: Wed, 4 Mar 2015 13:04:29 +0100 From: "Michael S. Tsirkin" Message-ID: <20150304120429.GA28121@redhat.com> References: <1425390913-17726-1-git-send-email-kraxel@redhat.com> <20150303174201.GD21824@redhat.com> <1425466550.8389.10.camel@nilsson.home.kraxel.org> <20150304110444.GB27463@redhat.com> <1425469610.8389.29.camel@nilsson.home.kraxel.org> <20150304115135.GB28099@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150304115135.GB28099@redhat.com> Subject: Re: [Qemu-devel] [PATCH] virtio-pci: make pci bar layout more flexible. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: "Michael S. Tsirkin" , qemu-devel@nongnu.org, Anthony Liguori On Wed, Mar 04, 2015 at 12:51:35PM +0100, Michael S. Tsirkin wrote: > On Wed, Mar 04, 2015 at 12:46:50PM +0100, Gerd Hoffmann wrote: > > On Mi, 2015-03-04 at 12:04 +0100, Michael S. Tsirkin wrote: > > > On Wed, Mar 04, 2015 at 11:55:50AM +0100, Gerd Hoffmann wrote: > > > > Hi, > > > > > > > > > > VirtIOPCIProxy subclasses which need additional pci bars, such as > > > > > > virtio-vga, just need to make sure they register the additinal bars > > > > > > before initializing virtio-pci, so the superclass can see the registered > > > > > > bars and shuffle around the virtio bars accordingly. > > > > > > > > > > I think I prefer we just DTRT and keep same layouts for everyone by > > > > > default: isn't there a layout that is good for everybody? > > > > > > > > I want bar #2 for the vga framebuffer for virtio-vga. Which conflicts > > > > with bar #2 being used for the modern bar in todays code. > > > > > > OK, and IIUC you are saying that using bar #2 for that is a requirement for > > > vga to work? > > > > Makes things alot easier as seavgabios has support for virtio-vga (in > > vga compat mode) already and expects the framebuffer being in bar #2. > > > > It's not a _really_ hard requirement though. > > > > cheers, > > Gerd > > > > Easy is good, I think we don't really care where the modern bar is, > let's just move it for everyone, and add a comment explaining the > motivation. OTOH if we really want to make it flexible, we can add a new virtio pci capability, with a new cfg_type value, say 0x6, and use that to describe BAR and offset for vga use. I'm not sure I understand all the implications though. > -- > MST