Re: [Qemu-devel] [RFC QEMU PATCH 8/8] qmp: add a qmp command 'query-nvdimms' to get plugged NVDIMM devices

[Haozhong Zhang]

On 10/10/16 14:16, Eric Blake wrote:
> On 10/09/2016 07:34 PM, Haozhong Zhang wrote:
> > Xen uses this command to get the backend resource, guest SPA and size of
> > NVDIMM devices so as to map them to guest.
> > 
> > Signed-off-by: Haozhong Zhang <address@hidden>
> > ---
> > Cc: Markus Armbruster <address@hidden>
> 
> > +++ b/docs/qmp-commands.txt
> > @@ -3800,3 +3800,39 @@ Example for pc machine type started with
> >              "props": {"core-id": 0, "socket-id": 0, "thread-id": 0}
> >           }
> >         ]}
> > +
> > +EQMP
> > +
> > +    {
> > +        .name       = "query-nvdimms",
> > +        .args_type  = "",
> > +        .mhandler.cmd_new = qmp_marshal_query_nvdimms,
> 
> Needs rebasing - we no longer need SQMP/EQMP sections or callouts to the
> initializers, now that commit bd6092e4 has automated the mapping of QAPI
> to command registration.
>

good to know this, will change in next version

> > +    },
> > +
> > +SQMP
> > +Show plugged NVDIMM devices
> > +---------------------------
> > +
> > +Arguments: None.
> > +
> > +Example for pc machine type started with
> > +-object memory-backend-file,id=mem1,mem-path=/path/to/nvm1,size=4G
> > +-device nvdimm,id=nvdimm1,memdev=mem1
> > +-object memory-backend-file,id=mem2,mem-path=/path/to/nvm2,size=8G
> > +-device nvdimm,id=nvdimm2,memdev=mem2:
> > +
> > +-> { "execute": "query-nvdimms" }
> > +<- { "returns": [
> > +      {
> > +         "mem-path": "/path/to/nvm1",
> > +    "slot": 0,
> 
> TAB damage; please fix.
>

will fix

> > +    "spa": 17179869184,
> > +    "length": 4294967296
> > +      },
> > +      {
> > +         "mem-path": "/path/to/nvm2",
> > +    "slot": 1,
> > +    "spa": 21474836480,
> > +    "length": 8589934592
> > +      }
> > +   ]}
> 
> > +++ b/qapi-schema.json
> > @@ -4646,3 +4646,32 @@
> >  # Since: 2.7
> >  ##
> >  { 'command': 'query-hotpluggable-cpus', 'returns': ['HotpluggableCPU'] }
> > +
> > +##
> > +# @NvdimmInfo
> > +#
> > +# Information about an NVDIMM device.
> > +#
> > +# @mem-path: the backend file of the NVDIMM device
> > +#
> > +# @slot: the slot index of the NVDIMM device
> > +#
> > +# @spa: the 64-bit SPA base address of the NVDIMM device
> > +#
> > +# @length: the 64-bit size in bytes of the NVDIMM device
> > +#
> > +# Since 2.8
> > +##
> > +{ 'struct': 'NvdimmInfo',
> > +  'data': {'mem-path' : 'str', 'slot': 'int', 'spa': 'int', 'length': 
> > 'int'} }
> > +
> > +##
> > +# @query-nvdimms:
> > +#
> > +# Returns information about each NVDIMM device
> > +#
> > +# Returns: a list of @NvdimmInfo for each device
> > +#
> > +# Since: 2.8
> > +##
> > +{ 'command': 'query-nvdimms', 'returns': ['NvdimmInfo'] }
> > 
> 
> Is this something that can be added to the existing query-memdev or
> query-memory-devices command, instead of needing a new command?
>

Both query-memdev and query-memory-devices do not tell whether a
device is NVDIMM. If adding an optional argument to existing a qmp
command does not break backwards compatibility, I propose to add an
argument "nvdimm" to query-memory-devices which controls whether this
command to return all memory devices or only NVDIMM devices.

Thanks,
Haozhong