[PATCH v6] Documentation, dt, numa: Add note to empty NUMA node
From: Gavin Shan <hidden>
Date: 2021-07-11 00:56:39
Also in:
lkml
Subsystem:
open firmware and flattened device tree bindings, the rest · Maintainers:
Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
The empty memory nodes, where no memory resides in, are allowed. For these empty memory nodes, the 'len' of 'reg' property is zero. The NUMA node IDs are still valid and parsed, but memory may be added to them through hotplug afterwards. I finds difficulty to get where it's properly documented. So lets add a section for empty memory nodes in NUMA binding document. Also, the 'unit-address', equivalent to 'base-address' in the 'reg' property of these empty memory nodes is suggested to be the summation of highest memory address plus the NUMA node ID. Signed-off-by: Gavin Shan <redacted> Acked-by: Randy Dunlap <redacted> --- v6: Drop '0x' in 'unit-address' as Rob suggested --- Documentation/devicetree/bindings/numa.txt | 61 +++++++++++++++++++++- 1 file changed, 60 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt
index 21b35053ca5a..7a7f281a401f 100644
--- a/Documentation/devicetree/bindings/numa.txt
+++ b/Documentation/devicetree/bindings/numa.txt@@ -103,7 +103,66 @@ Example: }; ============================================================================== -4 - Example dts +4 - Empty memory nodes +============================================================================== + +Empty memory nodes, which no memory resides in, are allowed. The 'length' +field of the 'reg' property is zero, but the 'base-address' is a dummy +address and invalid. The 'base-address' could be the summation of highest +memory address plus the NUMA node ID. However, the NUMA node IDs and +distance maps are still valid and memory may be added into them through +hotplug afterwards. + +Example: + + memory@0 { + device_type = "memory"; + reg = <0x0 0x0 0x0 0x80000000>; + numa-node-id = <0>; + }; + + memory@80000000 { + device_type = "memory"; + reg = <0x0 0x80000000 0x0 0x80000000>; + numa-node-id = <1>; + }; + + /* Empty memory node */ + memory@100000002 { + device_type = "memory"; + reg = <0x1 0x2 0x0 0x0>; + numa-node-id = <2>; + }; + + /* Empty memory node */ + memory@100000003 { + device_type = "memory"; + reg = <0x1 0x3 0x0 0x0>; + numa-node-id = <3>; + }; + + distance-map { + compatible = "numa-distance-map-v1"; + distance-matrix = <0 0 10>, + <0 1 20>, + <0 2 40>, + <0 3 20>, + <1 0 20>, + <1 1 10>, + <1 2 20>, + <1 3 40>, + <2 0 40>, + <2 1 20>, + <2 2 10>, + <2 3 20>, + <3 0 20>, + <3 1 40>, + <3 2 20>, + <3 3 10>; + }; + +============================================================================== +5 - Example dts ============================================================================== Dual socket system consists of 2 boards connected through ccn bus and
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2.23.0