gmod-lcpu/ideas.md

LCPU Idea/Working Model Sheet

This is basically the working ideas for the LCPU project.

Core features

• CPU SENTs
  • RISC-V rv32ima core
    • Would supporting more than one CPU core type be worthwhile? If so, the project is relatively setup for such workflow...
  • Controllable paramaters (RAM size, ...)

Code upload

• Upload a raw binary to execute, generated from any user tooling (goes into server data/lcpu/users/[steamid]/)
  • Yes, this means you can run Linux in GMod. No, I'm not sorry.

Integrated simple project workflow (WIP, not in the addon yet)

• Uses official RISC-V GCC toolchain

  • In a podman container for jailing reasons?

• Write assembly/C/C++ code using a tiny project system (source for them would go in server data/lcpu/users/[steamid]/projects/[project])

  • At the root of a project, a project.json file is expected to exist, with contents like:

  {
  	"Project": {
  		"Name": "test",
  
  		// Define all build configurations here
  		"Configurations": {
  			"Debug": {
  				"CCompileFlags": "-O0 ${BaseCCompileFlags}",
  				"CppCompileFlags": "-O0 ${BaseCppCompileFlags}"
  			},
  			"Release": {
  				"CCompileFlags": "-O2 ${BaseCCompileFlags}",
  				"CppCompileFlags": "-O2 ${BaseCppCompileFlags}",
  				// If a variable is unset it will usually default to
  				// ${Base${VariableName}}
  				"LinkerFlags": "-Wl,--gc-sections ${BaseLinkerFlags}"
  			}
  		},
  
  		"Sources": [
  			"binary.ld",
  			"start.S",
  			"main.c"
  		]
  	}
  }
  

  • BaseCCompileFlags and BaseCppCompileFlags are defaulted to sane values for each language.

  • This will be transpiled into a Makefile by the addon.

    • A standalone tool will be provided and used for transpiling project.json to a Makefile (and maybe even built into the container and transpiled there, to reduce the actions on the host to just the podman run?)
    • which, when a Build is done in GMod; is then run with make in a temporary podman container which only has access to the source code folder for the project (and nothing else, besides riscv tools which are in the image).
      • Command line is probably something like make CONFIG=${config}
    • the output binary will be stored alongside the source code on the server side, with a name like ${name}-${config}.bin
      • This file can then be selected for loading (without needing to be uploaded from the client).

• There is no conditional compilation in the project.json system

  • All files in a project are always built by that project.

• No notion of subprojects/build dependencies

  • This is meant to be simple for easy development in GMod. If you want complex build features you can export the project onto your own computer and use lcpu_projgen to generate Makefiles (which you can then maintain)

• Text editor used to edit project source files

  • Use the Wire editor? (we need wiremod anyways, and the text editor is.. OK I suppose.)
    • Or: https://github.com/Metastruct/gmod-monaco
      • https://github.com/JustMrPhoenix/Noir/tree/master

• Some example projects?

  • A simple bare metal "Hello World"
  • I joke about it, but an RTOS would be really nice and a good stress test of the project system (for usage in "real" projects.)

Moderation/administration tools

• Admin controlled per-user max RAM size (default 64mb)

• Admin controlled per-user max LCPU entity count (default 8)

• Admin controled global (affects all placed LCPUs) scheduler cycle rate/instruction count. - default is 0.1/1024 instructions

Addon interopability

• Wiremod interopability
  • Wiremod GPIO peripheral (to interface with wire world)
  • special Console Screen peripheral (interfacing specifically with it)
  • frambuffer peripheral which uses the Digital Screen