From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36276) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c9wuy-00077N-HK for qemu-devel@nongnu.org; Thu, 24 Nov 2016 11:30:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c9wuu-0002Be-Fu for qemu-devel@nongnu.org; Thu, 24 Nov 2016 11:30:36 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51892 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c9wuu-0002BM-9o for qemu-devel@nongnu.org; Thu, 24 Nov 2016 11:30:32 -0500 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uAOGTuWp127833 for ; Thu, 24 Nov 2016 11:30:31 -0500 Received: from e06smtp14.uk.ibm.com (e06smtp14.uk.ibm.com [195.75.94.110]) by mx0b-001b2d01.pphosted.com with ESMTP id 26wxhs8ybu-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 24 Nov 2016 11:30:30 -0500 Received: from localhost by e06smtp14.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 24 Nov 2016 16:30:27 -0000 Date: Thu, 24 Nov 2016 17:30:19 +0100 From: Cornelia Huck In-Reply-To: <20161124015119.GS17795@umbus.fritz.box> References: <1479777133-23567-1-git-send-email-ehabkost@redhat.com> <20161122223450.GD21830@thinpad.lan.raisama.net> <20161123171047.GA27297@thinpad.lan.raisama.net> <20161124015119.GS17795@umbus.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20161124173019.1d3f1b39.cornelia.huck@de.ibm.com> Subject: Re: [Qemu-devel] -nodefaults and available buses (was Re: [RFC 00/15] qmp: Report supported device types on 'query-machines') List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: Eduardo Habkost , Peter Maydell , Alex Williamson , Michael Roth , "Michael S. Tsirkin" , Alexey Kardashevskiy , Mark Cave-Ayland , qemu-devel@nongnu.org, Markus Armbruster , Beniamino Galvani , libvir-list@redhat.com, Greg Kurz , qemu-arm@nongnu.org, qemu-ppc@nongnu.org, Laine Stump , "Edgar E. Iglesias" , Marcel Apfelbaum , Paolo Bonzini , Andrea Bolognani , Artyom Tarasenko , Jia Liu On Thu, 24 Nov 2016 12:51:19 +1100 David Gibson wrote: > On Wed, Nov 23, 2016 at 03:10:47PM -0200, Eduardo Habkost wrote: > > (CCing the maintainers of the machines that crash when using > > -nodefaults) > > > > On Tue, Nov 22, 2016 at 08:34:50PM -0200, Eduardo Habkost wrote: > > [...] > > > "default defaults" vs "-nodefault defaults" > > > ------------------------------------------- > > > > > > Two bad news: > > > > > > 1) We need to differentiate buses created by the machine with > > > "-nodefaults" and buses that are created only without > > > "-nodefaults". > > > > > > libvirt use -nodefaults when starting QEMU, so knowing which > > > buses are available when using -nodefaults is more interesting > > > for them. > > > > > > Other software, on the other hand, might be interested in the > > > results without -nodefaults. > > > > > > We need to be able model both cases in the new interface. > > > Suggestions are welcome. > > > > The good news is that the list is short. The only[1] machines > > where the list of buses seem to change when using -nodefaults > > are: > > > > * mpc8544ds > > * ppce500 > > * mpc8544ds > > * ppce500 > > * s390-ccw-virtio-* > > > > On all cases above, the only difference is that a virtio bus is > > available if not using -nodefaults. > > Hrm.. that's odd. Well, it makes sense for the s390 which has special > virtio arrangements. I don't think it makes much sense for s390 either... is this a 'virtio' bus or a 'virtio-{pci,ccw}' bus? The transport bus should be present with -nodefaults; the virtio bus is basically a glue bus for virtio devices... > However, the others are all embedded ppc > machines, whose virtio should be bog-standard virtio-pci. I'm > wondering if the addition of the virtio "bus" is a side-effect of the > NIC or storage device created without -nodefaults being virtio. I'd suspect the default NICs (which are virtio at least in the s390 case).