In AMP startup process, Linux and RT-Thread RTOS start up independently, with their
configuration entry set in the DTS of U-Boot, which separates Linux domain and RTOS
domain. In OpenSBI, each core will jump to a different address based on different
configurations. RT-Thread does not jump to the second stage of U-Boot, but directly
jumps from OpenSBI to RT-Thread.
RT-Thread Side
The
rtthread.bin and
u-boot.bin files of
the RT-Thread are used together to generate
visionfive2_fw_payload_amp.img, and SPL image
u-boot-amp-spl.bin.normal.out will read this image to the
starting physical address of DDR, which is
0×40000000. The
components of this image are as follows:
Table 1. Memory Address Range
| RT-Thread Side |
Range |
Memory |
Reclaim Linux kernel or not? |
| OpenSBI |
0×40000000 - 0×401fffff |
2M |
Always keep it |
| U-Boot (S Mode) |
0×40200000- 0×4032ffff |
1.19M |
Linux kernel will be reclaimed after startup |
| RT-Thread |
0×6e800000 - 0×6effffff |
8M |
First U-Boot SPL loads RT-Thread into memory, the starting
address is 0x40330000, and then migrates to
0x6e800000. The
0x40330000 address will be
reclaimed. |
Linux Side
The Linux side has reserved 28M for AMP, with shared memory set to 4M. The memory distribution is as follows:
Table 2. Memory Address Range
| Linux Side |
Range |
Memory |
| Shared Memory |
0×6e400000 - 0×6e7fffff |
4M |
| RT-Thread code, stack space |
0×6e800000 - 0×6effffff |
8M |
| RT-Thread code, stack space |
0×6f000000 - 0×6fffffff |
16M |
