initial commit for open source NoC IP

doc/system_memory_map.md

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+# System Memory Map
+
+## 1 Home Node to Memory Channel
+
+### 1.1 Range-based: non-hashed SN target ID
+
+use reg to direct assign a range of memory address to specific memory channel or io device
+
+### 1.2 Range-based: hashed SN target ID
+
+#### 1.2.1 UMA mode
+
+use reg to assign a range of memory address, for 4 home node, 4 memory channel:
+1. use PA[7:6] to interleave among memony channels (cache line interleave)
+2. for unbalanced memory size among memory channels, use to smallest size channel to interleave, and other memory use direct assign
+
+| PA bit num        | msb | ... | 8   | 7   | 6   | 5 - 0       |
+| ----------------- | --- | --- | --- | --- | --- | ----------- |
+| Interleaving type |     |     |     | CH  | CH  | line offest |
+
+CH: Channel interleaving
+
+#### 1.2.2 NUMA mode
+
+use reg to assign a range of memory address, for 4 home node, 4 memory channel:
+1. use PA[6] to interleave among memony channels (cache line interleave)
+2. use PA[msb] to interleave among nodes
+3. for unbalanced memory size among memory channels, use to smallest size channel to interleave, and other memory use direct assign
+
+| PA bit num        | msb | ... | 8   | 7   | 6   | 5 - 0       |
+| ----------------- | --- | --- | --- | --- | --- | ----------- |
+| Interleaving type | ND  |     |     | CH  | CH  | line offest |
+
+ND: Node interleaving, CH: Channel interleaving
+
+## 2 Request Node to Home Node
+
+### 2.1 Non-hashed regions
+
+A given memory partition is assigned to an individual targetID (non-hashed), for:
+1. PLIC(highest priority);
+2. IO space;
+3. Directly assigned memory range
+
+### 2.2 Hashed memory region or non-hashed mode of hashed memory region
+
+#### 2.2.1 NUCA mode
+
+use reg to assign a range of memory address for one core/cluster to its nearest home node, 
+it can be configured at reset.