4/29/2020
Godson 3A1000 Processor User Manual
17
9
9
0x9000_0000_0000
0xa000_0000_0000
10
0xa
0xa000_0000_0000
0xb000_0000_0000
11
0xb
0xb000_0000_0000
0xc000_0000_0000
12
0xc
0xc000_0000_0000
0xd000_0000_0000
13
0xd
0xd000_0000_0000
0xe000_0000_0000
14
0xe
0xe000_0000_0000
0xf000_0000_0000
15
0xf
0xf000_0000_0000
0x1_0000_0000_0000
8
Page 21
Godson 3A1000 Processor User Manual Part 1
Within each node, the 44-bit address space is further evenly distributed to a maximum of 8 devices that may be connected within the node
Prepare. Among them, the lower 43 bits of addresses are owned by 4 level 2 cache modules, and the higher 43 bits of addresses are further according to the address [43:42]
Bits are distributed to devices connected to the 4 directional ports. According to the different configuration of chip and system structure, if a port
If no slave device is connected, the corresponding address space is reserved address space, and access is not allowed.
Table 2-3 Address distribution in nodes
device
Address [43:41]
Start address within the node
Node end address
Level 2 Cache
0,1,2,3
0x000_0000_0000
0x800_0000_0000
east
4
0x800_0000_0000
0xa00_0000_0000
south
5
0xa00_0000_0000
0xc00_0000_0000
oo
6
0xc00_0000_0000
0xe00_0000_0000
north
7
0xe00_0000_0000
0x1000_0000_0000
For example, the base address of the east port device of node 0 is 0x0800_0000_0000, and the base address of the east port device of node 1
0x1800_0000_0000, and so on.
Unlike the mapping relationship of direction ports, Loongson 3A1000 can determine the second level according to the actual application access behavior
Cache cross-addressing mode. The four Level 2 Cache modules in the node correspond to a total of 43 bits of address space, and each 2
The address space corresponding to the level module is determined according to one of the two selection bits of the address bit, and can be dynamically configured by software
modify. The configuration register named SCID_SEL is set in the system to determine the address selection bits, as shown in the following table. In default
In this case, it is distributed by means of [6: 5] status hash, that is, two bits of address [6: 5] determine the corresponding level 2 cache number.
The register address is 0x3FF00400.
Table 2-4 Address distribution in nodes
SCID_SEL
Address bit selection
SCID_SEL
Address bit selection
4'h0
6: 5
4'h8
23:22
4'h1
9: 8
4'h9
25:24
4'h2
11:10
4'ha
27:26
4'h3
13:12
4'hb
29:28
4'h4
15:14
4'hc
31:30
4'h5
17:16
4'hd
33:32
4'h6
19:18
4'he
35:34
4'h7
21:20
4'hf
37:36
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