Subject: Re: [PATCH] powerpc/numa: Restrict possible nodes based on platform

From: Michael Ellerman <[email-masked]>
Date: Tue, 07 Jul 2020 15:02:17 +1000

Srikar Dronamraju <[email-masked]> 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