Re: [Qemu-devel] [Qemu-ppc] [QEMU-PPC] [PATCH V3 0/6] target/ppc: Rework spapr_caps

[Alexey Kardashevskiy <aik@ozlabs.ru>]

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On 19/01/18 13:22, David Gibson wrote:
> On Thu, Jan 18, 2018 at 04:55:39PM +0100, Andrea Bolognani wrote:
>> On Thu, 2018-01-18 at 15:27 +1100, David Gibson wrote:
>>>> I looked further and device-list-properties looks like it would
>>>> do the trick; however it doesn't seem to work for machines:
>>>>
>>>>   {"execute": "device-list-properties",
>>>>    "arguments": {"typename": "spapr-2.11-machine"}}
>>>>   {"error": {"class": "GenericError",
>>>>              "desc": "Parameter 'typename' expects device"}}
>>>>
>>>> It works fine for the likes of virtio-scsi-pci and even
>>>> power9_v2.0-powerpc64-cpu, though. Any ideas? :)
>>>
>>> I'm guessing it's because machines aren't descended from TYPE_DEVICE.
>>>
>>> Dammit.  I really can't see a reasonable way of addressing this other
>>> than improving qapi in general to have a way of reporting machine
>>> class properties.  Adding something ad-hoc for just these properties
>>> of this machine seems like madness.
>>>
>>> Nor can I think of a place to put these that would be both sensible
>>> and more discoverable with existing mechanisms.
>>
>> The relationship between QOM/QAPI/QMP is not very clear in my mind,
> 
> You and me both :/
> 
>> as you might have guessed from my messages, so I don't think I can
>> offer much useful input. But if the properties are registered using
>> the same mechanism both for devices and machines, then maybe there
>> should be a QMP command that can list them regardless of the parent
>> type? object-list-properties or something like that.
> 
> So, it's a bit complicated.  The underlying mechanism is QOM
> properties in all cases.

There are 2 types of properties really.

typedef struct DeviceClass {
[...]
    Property *props;

These are printed by QMP's device-list-properties. Machine is not a device
so we do not see them.


struct ObjectClass
{
[...]
    GHashTable *properties;

These are printed by qom-list/get but these QMP commands take path as an
argument and therefore require instances, not classes.


DeviceClass::props migrate to ObjectClass::properties in device_initfn.


So I guess we will either need to:
- merge all the properties to Object/ObjectClass or
- rename&teach device-list-properties to work with objects rather than
devices or
- add qom-list-properties which will only print QOM properties.


The latter is fairly simple, I'll post an rfc patch in few minutes, it will
do like this:


{"execute": "qom-list-properties", "arguments": {"typename":
"pseries-2.11-machine"}}


{   'return': [   {   'description': 'Set on/off to enable/disable graphics '
                                     'emulation',
                      'name': 'graphics',
                      'type': 'bool'},
                  {   'description': 'The first phandle ID we may generate '
                                     'dynamically',
                      'name': 'phandle-start',
                      'type': 'int'},
                  {   'description': 'Include guest memory in  a core dump',
                      'name': 'dump-guest-core',
                      'type': 'bool'},
                  {   'description': 'Configure KVM in-kernel irqchip',
                      'name': 'kernel-irqchip',
                      'type': 'OnOffSplit'},
                  {   'description': 'Accelerator list',
                      'name': 'accel',
                      'type': 'string'},
                  {   'description': 'Linux kernel command line',
                      'name': 'append',
                      'type': 'string'},
                  {   'description': 'Dump current dtb to a file and quit',
                      'name': 'dumpdtb',
                      'type': 'string'},
                  {   'description': 'Set on/off to enable/disable igd '
                                     'passthrou',
                      'name': 'igd-passthru',
                      'type': 'bool'},
                  {   'description': 'Overrides the "compatible" property of '
                                     'the dt root node',
                      'name': 'dt-compatible',
                      'type': 'string'},
                  {   'description': 'Linux kernel image file',
                      'name': 'kernel',
                      'type': 'string'},
                  {   'description': 'Set on/off to enable/disable usb',
                      'name': 'usb',
                      'type': 'bool'},
                  {   'description': 'Set on to disable self-describing '
                                     'migration',
                      'name': 'suppress-vmdesc',
                      'type': 'bool'},
                  {   'description': 'Linux kernel device tree file',
                      'name': 'dtb',
                      'type': 'string'},
                  {   'description': 'Firmware image',
                      'name': 'firmware',
                      'type': 'string'},
                  {   'description': 'Enable/disable memory merge support',
                      'name': 'mem-merge',
                      'type': 'bool'},
                  {   'description': 'Linux initial ramdisk file',
                      'name': 'initrd',
                      'type': 'string'},
                  {   'description': 'Set on to enforce configuration section '
                                     'migration',
                      'name': 'enforce-config-section',
                      'type': 'bool'},
                  {   'description': 'KVM shadow MMU size',
                      'name': 'kvm-shadow-mem',
                      'type': 'int'},
                  {   'description': 'Allow Decimal Floating Point (DFP)',
                      'name': 'cap-dfp',
                      'type': 'bool'},
                  {   'description': 'Allow Hardware Transactional Memory '
                                     '(HTM)',
                      'name': 'cap-htm',
                      'type': 'bool'},
                  {   'description': 'Allow Vector Scalar Extensions (VSX)',
                      'name': 'cap-vsx',
                      'type': 'bool'},
                  {'name': 'type', 'type': 'string'},
                  {   'description': 'Resizing of the Hash Page Table '
                                     '(enabled, disabled, required)',
                      'name': 'resize-hpt',
                      'type': 'string'},
                  {   'description': 'Maximum permitted CPU compatibility '
                                     'mode. Valid values are power6, power7, '
                                     'power7+, power8, power9.',
                      'name': 'max-cpu-compat',
                      'type': 'string'},
                  {   'description': 'Use dedicated hotplug event mechanism
in '
                                     'place of standard EPOW events when '
                                     'possible (required for memory
hot-unplug '
                                     'support)',
                      'name': 'modern-hotplug-events',
                      'type': 'bool'},
                  {   'description': 'Virtual SMT: KVM behaves as if this
were '
                                     "the host's SMT mode",
                      'name': 'vsmt',
                      'type': 'uint32'},
                  {   'description': 'Specifies the KVM virtualization mode '
                                     '(HV, PR)',
                      'name': 'kvm-type',
                      'type': 'string'},
                  {'name': 'vfio-no-msix-emulation', 'type': 'bool'}]}


-- 
Alexey


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