The current ARM DT topology description provides the operating system with a topological view of the system that is based on leaf nodes representing either cores or threads (in an SMT system) and a hierarchical set of cluster nodes that creates a hierarchical topology view of how those cores and threads are grouped. As opposed to the ACPI topology description ([1], PPTT table), this hierarchical representation of clusters does not allow to describe what topology level actually represents the physical package boundary, which is a key piece of information to be used by an operating system to optimize resource allocation and scheduling. Define an optional, backward compatible boolean property for cluster nodes that, by reusing the ACPI nomenclature, add to the ARM DT topological description a binding to define what cluster level represents a physical package boundary. [1] http://www.uefi.org/sites/default/files/resources/ACPI_6_2.pdf Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> Cc: Rob Herring <robh+dt@xxxxxxxxxx> Cc: Sudeep Holla <sudeep.holla@xxxxxxx> Cc: Jeremy Linton <jeremy.linton@xxxxxxx> Cc: Morten Rasmussen <morten.rasmussen@xxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> --- Documentation/devicetree/bindings/arm/topology.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/devicetree/bindings/arm/topology.txt b/Documentation/devicetree/bindings/arm/topology.txt index de9eb0486630..8e78d76b0671 100644 --- a/Documentation/devicetree/bindings/arm/topology.txt +++ b/Documentation/devicetree/bindings/arm/topology.txt @@ -109,6 +109,15 @@ Bindings for cluster/cpu/thread nodes are defined as follows: The cluster node name must be "clusterN" as described in 2.1 above. A cluster node can not be a leaf node. + Properties for cluster nodes: + + - physical-package + Usage: optional + Value type: <empty> + Definition: if present the cluster node represents the + boundary of a physical package, whether socketed + or surface mounted. + A cluster node's child nodes must be: - one or more cluster nodes; or -- 2.15.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
