Srikar Dronamraju [off-list ref] writes:

As per PAPR, there are 2 device tree property
ibm,max-associativity-domains (which defines the maximum number of
domains that the firmware i.e PowerVM can support) and
ibm,current-associativity-domains (which defines the maximum number of
domains that the platform can support). Value of
ibm,max-associativity-domains property is always greater than or equal
to ibm,current-associativity-domains property.

Where is it documented?

It's definitely not in LoPAPR.

Powerpc currently uses ibm,max-associativity-domains  property while
setting the possible number of nodes. This is currently set at 32.
However the possible number of nodes for a platform may be significantly
less. Hence set the possible number of nodes based on
ibm,current-associativity-domains property.

$ lsprop /proc/device-tree/rtas/ibm,*associ*-domains
/proc/device-tree/rtas/ibm,current-associativity-domains
		 00000005 00000001 00000002 00000002 00000002 00000010
/proc/device-tree/rtas/ibm,max-associativity-domains
		 00000005 00000001 00000008 00000020 00000020 00000100

$ cat /sys/devices/system/node/possible ##Before patch
0-31

$ cat /sys/devices/system/node/possible ##After patch
0-1

Note the maximum nodes this platform can support is only 2 but the
possible nodes is set to 32.

But what about LPM to a system with more nodes?

cheers