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Loongson 3A3000 / 3B3000 Processor User Manual
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Because from the processor core, memory controller, HT controller to all levels of crossbar switches have been upgraded to varying degrees,
Therefore, compared with Loongson 3A1000, PMON needs to make some changes, mainly including the following necessary parts:
1. Remove the initialization operations of L1 Dcache, L1 Icache, Vcache, and L2 Cache after power-on (hardware completion);
2. After the CPU is powered on, close the Store Fill Buffer of all cores;
3. Immediately after the CPU is powered on, turn off the word write merge function of all cores;
4. If you need to maintain compatibility with 3A5, set the PRID hidden bit in the CP0 Diag register of all cores;
5. Modify the statements of jr rx and rx which are not register 31 in all assembly codes to jr $ 31;
6. Use code similar to 3B1500 to configure processor core, memory and node PLL;
7. Use the memory controller configuration and parameter training code similar to 3B1500;
8. If HT works in 1.0 mode, HT can only work in 8-bit mode;
9. If an SPI controller is used, the base address is changed from 0xBFE001F0 to 0xBFE00220;
In addition to these necessary changes, the following changes can be made to enhance the PMON function:
1. Modify the delay delay of the buzzer to ensure that the user can hear the buzzer;
2. Add support to shut down the defective core clock;
3. Remove part of the workaround of the 3A5 to 2h bridge HT controller in the code (still retain some workaround);
13.4 Guidelines for kernel changes
The following kernel changes are basically the same as 3A2000 / 3B2000, but need to be added in the corresponding part of the kernel
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Godson 3A3000 / 3B3000 Processor User Manual • Volume 1
3A3000 / 3B3000 processor support.