[PATCH V8 0/2] powerpc/dlpar: Correct display of hot-add/hot-remove CPUs and memory

Michael Bringmann mwb at linux.vnet.ibm.com
Wed Jul 12 03:35:26 AEST 2017

On Power systems with shared configurations of CPUs and memory, there
are some issues with association of additional CPUs and memory to nodes
when hot-adding resources.  These patches address some of those problems.

powerpc/hotplug: On systems like PowerPC which allow 'hot-add' of CPU
or memory resources, it may occur that the new resources are to be
inserted into nodes that were not used for these resources at bootup.
In the kernel, any node that is used must be defined and initialized
at boot.  In order to meet both needs, this patch adds a new kernel
command line option (numnodes=<int>) for use by the PowerPC
architecture-specific code that defines the maximum number of nodes
that the kernel will ever need in its current hardware environment.
The boot code that initializes nodes for PowerPC will read this value
and use it to ensure that all of the desired nodes are setup in the
'node_possible_map', and elsewhere.

powerpc/numa: Correct the currently broken capability to set the
topology for shared CPUs in LPARs.  At boot time for shared CPU
lpars, the topology for each shared CPU is set to node zero, however,
this is now updated correctly using the Virtual Processor Home Node
(VPHN) capabilities information provided by the pHyp. The VPHN handling
in Linux is disabled, if PRRN handling is present.

Signed-off-by: Michael Bringmann <mwb at linux.vnet.ibm.com>

Michael Bringmann (2):
  powerpc/hotplug: Add option to define max nodes allowing dynamic
      growth of resources.
  powerpc/numa: Update CPU topology when VPHN enabled
Changes in V8:
  -- Fix conditional compile bug.

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