[libvirt] -nodefaults and available buses (was Re: [Qemu-devel] [RFC 00/15] qmp: Report supported device types on 'query-machines')
(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.
Considering that the list is short, I plan to rename
'supported-device-types' to 'always-available-buses', and
document that it will include only the buses that are not
disabled by -nodefaults.
[1] I mean, the only ones from the set that don't crash with
-nodefaults. The ones below could not be tested:
2) A lot of machine-types won't start if using
"-nodefaults -machine <machine>" without any extra devices or
drives.
Lots of machines require some drives or devices to be created
(especially ARM machines that require a SD drive to be
available).
Some machines will make QEMU exit, some of them simply segfault.
I am looking for ways to work around it so we can still validate
-nodefaults-based info on the test code.
The following machines won't work with -nodefaults:
These make QEMU segfault:
* cubieboard
* petalogix-ml605
* or32-sim
* virtex-ml507
* Niagara
These exit with a "missing SecureDigital device" error:
* akita
* borzoi
* cheetah
* connex
* mainstone
* n800
* n810
* spitz
* sx1
* sx1-v1
* terrier
* tosa
* verdex
* z2
--
Eduardo