Changing Naxriscv instructions - command

[mdmriscv]

Hi,

I am a starter in this code and would like to initially change some Naxriscv instructions.

To provide some context, I was able to successfully compile and run litex, flash the board, and even boot Linux using Naxriscv as below:

python3 -m litex_boards.targets.digilent_nexys_video --cpu-type=naxriscv --bus-standard axi-lite --with-video-framebuffer --with-spi-sdcard --with-ethernet --xlen=64 --scala-args='rvc=true,rvf=true,rvd=true' --build --load

All good, thanks for those.

It seems that a way to change via changing the files located at pythondata/verilog/ext/NaxRiscv/src/main/scala/naxriscv/riscv because there are *.scala files and for example, the Rvi.scala file has the definitions of the instructions. Am I correct? Let's say that the following is possible: I want to remove one of the instructions (e.g. AMOADD) generate a riscv without this instruction. Let's say I comment all *.scala files in this folder and related usage.

What is the command I have to use to regenerate the bitstream?

I am not sure, but it seems that I have to add --scala-file=.../python-cpu-naxriscv/verilog/configs gen.scala to the command above? Anyway, it seems that if I do that that it still uses the verilog files (under verilog folder) and not the *.scala files I meant before.

Any help is more than welcome! Thanks much

[Dolu1990]

Hi,

Removing the AMOADD from that list would work : https://github.com/SpinalHDL/NaxRiscv/blob/8816542dc59579e82e419ecf93586215dcb3b902/src/main/scala/naxriscv/execute/AguPlugin.scala#L61

What is the command I have to use to regenerate the bitstream?

you will have to :

• delete the pythondata-cpu-naxriscv/pythondata_cpu_naxriscv/verilog/NaxRiscvLitex_*.v files
• run the commend you used with an additional --update-repo=no

but it seems that I have to add --scala-file=.../python-cpu-naxriscv/verilog/configs gen.scala to

Naa not realy, it is the default if i remember well.

Also, note https://github.com/enjoy-digital/litex/pull/1923 :)