K210 porting logs

[wyfcyx]

Following the step of @wangrunji0408, I want to port the tutorial from Qemu to K210, a RISC-V board which is cheap and simple, as an important part of the fourth edition of tutorial.
K210 is based on RISC-V spec 1.9.1, which was published about 4 years ago. So you can hardly find a toolchain or bootloader that fits it perfectly now. For example, OpenSBI 0.4/0.8 don't work normally on K210...
About 1 year and a half ago, rjgg tried to port rCore to K210 and succeed in the end. Here is his log. He modified OpenSBI 0.3 in order to support K210, you can find that version here.
How to use it to completing porting? It is at a relative ease. First, download the modified OpenSBI, and change the FW_PAYLOAD_ALIGN to 0x200000 since we want to put our kernel to 0x80200000 on memory. Then, merge the OpenSBI image(fw_payload.bin) and our kernel image into a big one using dd tool and finally burn it into flash.
Now, chapter 2 can run on K210 successfully. I will create a new branch about porting later.

[wyfcyx]

By the way, the related commit link of rjgg's work is here.

[wyfcyx]

I will close this issue and continue my porting work here.