On Thu, 24 Nov 2016 12:51:19 +1100 David Gibson <david@gibson.dropbear.id.au> 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).