
4/29/2020
Loongson 3A3000 / 3B3000 Processor User Manual
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Godson 3A3000 / 3B3000 Processor User Manual • Volume 1
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The slave devices corresponding to the address space of the first-level crossbar in Loongson 3A3000 / 3B3000 are as follows:
Table 2-3 Address distribution in nodes
device
Address [43:41]
Start address within the node
Node end address
Shared Cache
0,1,2,3
0x000_0000_0000
0x7FF_FFFF_FFFF
HT0 controller
6
0xC00_0000_0000
0xDFF_FFFF_FFFF
HT1 controller
7
0xE00_0000_0000
0xFFF_FFFF_FFFF
Unlike the mapping relationship of direction ports, Loongson 3A3000 / 3B3000 can be determined according to the actual application access behavior
Set the cross-addressing mode of shared cache. The 4 shared Cache modules in the node correspond to a total of 43 address spaces, and
The address space corresponding to each 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 [7: 6] status hash, that is, two bits of address [7: 6] determine the corresponding shared 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
7: 6
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
2.5 Distribution of physical address space within a node
The default distribution of the internal 44-bit physical address of each node of Loongson 3A3000 / 3B3000 processor is shown in the following table:
Table 2-2 44-bit physical address distribution in the node
starting address
End address
name
Explanation
0x0000_0000_0000
0x0000_0FFF_FFFF
RAM
Need to use two-level crossbar for mapping
0x0000_1000_0000
0x0000_1FFF_FFFF
Low speed IO Need to use two-level crossbar for mapping
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Godson 3A3000 / 3B3000 Processor User Manual • Volume 1
0x2000_0000_0000
0x2FFF_FFFF_FFFF
2
2
0x3000_0000_0000
0x3FFF_FFFF_FFFF
3
3
Loongson 3A3000 / 3B3000 uses a single-node 4-core configuration, so Loongson 3A3000 / 3B3000 chip integrated DDR
2.6 Address Routing Distribution and Configuration