4/29/2020
Loongson 3A3000 / 3B3000 Processor User Manual
17
16
sysclk * (clksel [3: 0] +30) must be 1.2GHz ~ 3.2GHz
sysclk is the input reference clock, which must be 20 ~ 40MHz
PCI_CONFIG [7: 0]
IO configuration control
7
HT bus cold start is forced to 1.0 mode
6: 4 needs to be set to 000
3
PCI master mode
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Godson 3A3000 / 3B3000 Processor User Manual • Volume 1
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2
Need to be set to 0
1
Use external PCI arbitration
0
Use SPI boot function
2.3 Cache
consistency
Loongson 3A3000 / 3B3000 maintains the cache between the processor and the I / O accessed through the HT port
It is consistent, but the hardware does not maintain the cache consistency of the I / O devices connected to the system through PCI. During driver development,
When DMA (Direct Memory Access) transmission is performed on a device connected via PCI, the software needs to perform Cache
Consistency maintenance.
2.4 Distribution of physical address space at the node level of the system
The system physical address distribution of Loongson No. 3 series processors adopts a globally accessible hierarchical addressing design
The extensions developed by the system are compatible. The physical address width of the entire system is 48 bits. According to the upper 4 bits of the address, the entire address sp
It is evenly distributed to 16 nodes, that is, each node is allocated 44-bit address space.
Loongson 3A3000 / 3B3000 processor can directly use 4 chips to connect directly to build CC-NUMA system.
The processor number is determined by the pin NODEID, and the address space of each chip is distributed as follows:
Table 2-2 Node-level system global address distribution
Chip node number (NODEID)
Address [47:44] bits
starting address
End address
0
0
0x0000_0000_0000
0x0FFF_FFFF_FFFF
1
1
0x1000_0000_0000
0x1FFF_FFFF_FFFF
2
2
0x2000_0000_0000
0x2FFF_FFFF_FFFF
3
3
0x3000_0000_0000
0x3FFF_FFFF_FFFF
Loongson 3A3000 / 3B3000 uses a single-node 4-core configuration, so Loongson 3A3000 / 3B3000 chip integrated DDR
The corresponding addresses of the memory controller, HT bus, and PCI bus are included from 0x0 (inclusive) to 0x1000_0000_0000 (not
The 44-bit address is in each node, and the 44-bit address space is further evenly distributed to the most likely connection within the node.
8 more devices. The lower 43 bits of addresses are owned by 4 shared cache modules, and the higher 43 bits of addresses are further
The [43:42] bits are distributed to devices connected to the 4 directional ports. According to the different configuration of chip and system structure, if
If there is no slave device connected to a port, the corresponding address space is reserved address space, and access is not allowed.