320 lines
7.8 KiB
Plaintext
320 lines
7.8 KiB
Plaintext
==============================================================================
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NUMA binding description.
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==============================================================================
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==============================================================================
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1 - Introduction
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==============================================================================
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Systems employing a Non Uniform Memory Access (NUMA) architecture contain
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collections of hardware resources including processors, memory, and I/O buses,
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that comprise what is commonly known as a NUMA node.
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Processor accesses to memory within the local NUMA node is generally faster
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than processor accesses to memory outside of the local NUMA node.
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DT defines interfaces that allow the platform to convey NUMA node
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topology information to OS.
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==============================================================================
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2 - numa-node-id
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==============================================================================
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For the purpose of identification, each NUMA node is associated with a unique
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token known as a node id. For the purpose of this binding
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a node id is a 32-bit integer.
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A device node is associated with a NUMA node by the presence of a
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numa-node-id property which contains the node id of the device.
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Example:
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/* numa node 0 */
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numa-node-id = <0>;
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/* numa node 1 */
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numa-node-id = <1>;
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==============================================================================
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3 - distance-map
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==============================================================================
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The optional device tree node distance-map describes the relative
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distance (memory latency) between all numa nodes.
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- compatible : Should at least contain "numa-distance-map-v1".
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- distance-matrix
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This property defines a matrix to describe the relative distances
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between all numa nodes.
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It is represented as a list of node pairs and their relative distance.
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Note:
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1. Each entry represents distance from first node to second node.
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The distances are equal in either direction.
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2. The distance from a node to self (local distance) is represented
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with value 10 and all internode distance should be represented with
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a value greater than 10.
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3. distance-matrix should have entries in lexicographical ascending
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order of nodes.
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4. There must be only one device node distance-map which must
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reside in the root node.
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5. If the distance-map node is not present, a default
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distance-matrix is used.
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Example:
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4 nodes connected in mesh/ring topology as below,
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0_______20______1
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20 20
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|_______________|
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3 20 2
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if relative distance for each hop is 20,
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then internode distance would be,
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0 -> 1 = 20
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1 -> 2 = 20
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2 -> 3 = 20
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3 -> 0 = 20
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0 -> 2 = 40
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1 -> 3 = 40
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and dt presentation for this distance matrix is,
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distance-map {
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compatible = "numa-distance-map-v1";
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distance-matrix = <0 0 10>,
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<0 1 20>,
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<0 2 40>,
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<0 3 20>,
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<1 0 20>,
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<1 1 10>,
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<1 2 20>,
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<1 3 40>,
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<2 0 40>,
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<2 1 20>,
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<2 2 10>,
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<2 3 20>,
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<3 0 20>,
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<3 1 40>,
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<3 2 20>,
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<3 3 10>;
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};
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==============================================================================
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4 - Empty memory nodes
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==============================================================================
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Empty memory nodes, which no memory resides in, are allowed. There are no
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device nodes for these empty memory nodes. However, the NUMA node IDs and
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distance maps are still valid and memory may be added into them through
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hotplug afterwards.
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Example:
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memory@0 {
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device_type = "memory";
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reg = <0x0 0x0 0x0 0x80000000>;
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numa-node-id = <0>;
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};
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memory@80000000 {
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device_type = "memory";
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reg = <0x0 0x80000000 0x0 0x80000000>;
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numa-node-id = <1>;
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};
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/* Empty memory node 2 and 3 */
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distance-map {
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compatible = "numa-distance-map-v1";
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distance-matrix = <0 0 10>,
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<0 1 20>,
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<0 2 40>,
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<0 3 20>,
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<1 0 20>,
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<1 1 10>,
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<1 2 20>,
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<1 3 40>,
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<2 0 40>,
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<2 1 20>,
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<2 2 10>,
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<2 3 20>,
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<3 0 20>,
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<3 1 40>,
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<3 2 20>,
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<3 3 10>;
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};
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==============================================================================
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5 - Example dts
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==============================================================================
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Dual socket system consists of 2 boards connected through ccn bus and
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each board having one socket/soc of 8 cpus, memory and pci bus.
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memory@c00000 {
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device_type = "memory";
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reg = <0x0 0xc00000 0x0 0x80000000>;
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/* node 0 */
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numa-node-id = <0>;
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};
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memory@10000000000 {
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device_type = "memory";
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reg = <0x100 0x0 0x0 0x80000000>;
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/* node 1 */
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numa-node-id = <1>;
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};
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cpus {
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#address-cells = <2>;
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#size-cells = <0>;
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cpu@0 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x0>;
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enable-method = "psci";
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/* node 0 */
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numa-node-id = <0>;
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};
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cpu@1 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x1>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@2 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x2>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@3 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x3>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@4 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x4>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@5 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x5>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@6 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x6>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@7 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x7>;
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enable-method = "psci";
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numa-node-id = <0>;
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};
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cpu@8 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x8>;
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enable-method = "psci";
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/* node 1 */
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numa-node-id = <1>;
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};
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cpu@9 {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0x9>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@a {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xa>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@b {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xb>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@c {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xc>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@d {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xd>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@e {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xe>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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cpu@f {
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device_type = "cpu";
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compatible = "arm,armv8";
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reg = <0x0 0xf>;
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enable-method = "psci";
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numa-node-id = <1>;
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};
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};
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pcie0: pcie0@848000000000 {
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compatible = "arm,armv8";
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device_type = "pci";
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bus-range = <0 255>;
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#size-cells = <2>;
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#address-cells = <3>;
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reg = <0x8480 0x00000000 0 0x10000000>; /* Configuration space */
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ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>;
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/* node 0 */
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numa-node-id = <0>;
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};
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pcie1: pcie1@948000000000 {
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compatible = "arm,armv8";
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device_type = "pci";
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bus-range = <0 255>;
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#size-cells = <2>;
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#address-cells = <3>;
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reg = <0x9480 0x00000000 0 0x10000000>; /* Configuration space */
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ranges = <0x03000000 0x9010 0x00000000 0x9010 0x00000000 0x70 0x00000000>;
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/* node 1 */
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numa-node-id = <1>;
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};
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distance-map {
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compatible = "numa-distance-map-v1";
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distance-matrix = <0 0 10>,
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<0 1 20>,
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<1 1 10>;
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};
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