4/29/2020
Loongson 3A3000 / 3B3000 Processor User Manual
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Consistency request between 4 chips. The following provides two multiprocessor interconnection methods:
Four piece Loongson No. 3 interconnection structure
The four CPUs are connected in pairs to form a ring structure. Each CPU uses two 8-bit controllers of HT0 to connect with two adjacent chips,
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Among them, HTx_LO is the master device, and HTx_HI is the slave device, and the interconnection structure as shown below is obtained:
CPU0
HT0_
HI
HT0_
LO
HT1
_LO
CPU1
HT0_
HI
HT0_
LO
CPU3
HT0_
HI
HT0_
LO
CPU2 HT0_
HI
HT0_
LO
8-bit HT bus
8Bit
H
T
total
line
8-bit HT bus
8Bit
H
T
total
line
IO
8-bit HT bus
HT1
_HI
HT1
_HI
HT1
_HI
HT1
_HI
Figure 10- 2 Four-chip Loongson No. 3 interconnection structure
Loongson 3 interconnection routing
Loongson No. 3 interconnection routing adopts simple XY routing method. When routing, X followed by Y, taking four chips as an example, ID
The numbers are 00, 01, 10, and 11, respectively. If you send a request from 11 to 00, it is a route from 11 to 00, first go in the X direction,
Go from 11 to 10, then go in Y direction, and go from 10 to 00. And when the response of the request returns from 00 to 11, the routing first goes
X direction, from 00 to 01, and then Y direction, from 01 to 11. As you can see, these are two different routing lines. by
Due to the characteristics of this algorithm, we will adopt different methods when constructing the interconnection of two chips.
Two piece Loongson No. 3 interconnection structure
Due to the nature of the fixed routing algorithm, we have two different methods when constructing the interconnection of two chips. The first is to adopt
Use 8-bit HT bus interconnection. In this interconnection method, only 8-bit HT interconnection can be used between the two processors. Two chip numbers
They are 00 and 01 respectively. From the routing algorithm, we can know that when two chips access each other, they are interconnected by four chips.
Consistent 8-bit HT bus. As follows: