content: create rust_for_linux

content/posts/rust_for_linux.md

@@ -0,0 +1,156 @@
+---
+title: "Rust for Linux"
+date: 2024-09-27T10:53:59-05:00
+draft: false
+toc: false
+images:
+tags:
+  - kernel
+  - rust
+---
+
+**please check previous post [Debug Linux Kernel](./debug_linux_kernel.md), make sure you know how to debug linux kernel before starting trying to use rust for linux kernel**
+
+other details are documented in `linux/Documentation/rust/quick-start.rst`
+
+## Outline
+
+- compile `linux` with `rust`
+- sample code
+- rust-analyzer
+- hints
+- debug
+
+## Compile Linux with Rust Enabled
+
+**note: rust is added to mainline after `6.1`, so make sure you are using linux above this version**
+
+> make sure you have `llvm`, `clang`, `lld`, `rust` installed before this section
+
+as rust use `llvm` tool chain, we need to configure and compile linux with `llvm`:
+
+- configure linux with `Rust` and `LLVM`, for minimal config:
+
+```bash
+make LLVM=1 allnoconfig
+```
+
+- enable some essential features by:
+
+```bash
+make LLVM=1 menuconfig
+```
+
+> 64-bit kernel ---> yes
+> General setup ---> Initial RAM filesystem and RAM disk (initramfs/initrd) support ---> yes
+> General setup ---> Configure standard kernel features ---> Enable support for printk ---> yes
+> Executable file formats / Emulations ---> Kernel support for ELF binaries ---> yes
+> Executable file formats / Emulations ---> Kernel support for scripts starting with #! ---> yes
+> Device Drivers ---> Generic Driver Options ---> Maintain a devtmpfs filesystem to mount at /dev ---> yes
+> Device Drivers ---> Generic Driver Options ---> Automount devtmpfs at /dev, after the kernel mounted the rootfs ---> yes
+> Device Drivers ---> Character devices ---> Enable TTY ---> yes
+> Device Drivers ---> Character devices ---> Serial drivers ---> 8250/16550 and compatible serial support ---> yes
+> Device Drivers ---> Character devices ---> Serial drivers ---> Console on 8250/16550 and compatible serial port ---> yes
+> File systems ---> Pseudo filesystems ---> /proc file system support ---> yes
+> File systems ---> Pseudo filesystems ---> sysfs file system support ---> yes
+> Processor type and features ---> Linux guest support ---> Support for running PVH guests ---> yes
+
+- we need to fix rustc version to the version required by kernel:
+
+```bash
+rustup override set $(scripts/min-tool-version.sh rustc)
+```
+
+- check if `rust` is available:
+
+```bash
+make LLVM=1 rustavailable
+```
+
+until it says: Rust is available!
+
+and to fix all the error it yield to you, you may need to do:
+
+```bash
+rustup component add rust-src
+cargo install --locked bindgen-cli
+```
+
+- then, enable all the `rust-related` feature by:
+
+```bash
+make LLVM=1 menuconfig
+```
+
+> General setup ---> Rust support ---> yes
+> Kernel hacking ---> Rust hacking ---> Debug assertions ---> yes
+
+- compile kernel:
+
+```bash
+make LLVM=1 -j
+```
+
+## Sample code
+
+- enable `rust` sample code in kernel config by:
+
+```bash
+make LLVM=1 menuconfig
+```
+
+> Kernel hacking ---> Sample kernel code ---> Rust samples
+
+**and the sample code is located at `linux/samples/rust/`**
+
+you can refer to it for how to develop kernel module in `rust`
+
+## Rust Analyzer
+
+compile kernel with `rust-analyzer` support
+
+```bash
+make LLVM=1 -j rust-analyzer
+```
+
+which will give me: `rust-project.json`
+
+## Hints
+
+- **always rustfmt before commit**
+
+```bash
+make LLVM=1 -j rustfmt
+make LLVM=1 -j rustfmtcheck
+```
+
+- **always generate document**
+
+```bash
+make LLVM=1 -j rustdoc
+```
+
+- **use clippy**
+
+```bash
+make LLVM=1 -j CLIPPY=1
+```
+
+- **test code unrelated with kernel**
+
+```bash
+make LLVM=1 -j rusttest
+```
+
+## Test
+
+- enable `KUNIT`
+
+```bash
+make LLVM=1 menuconfig
+```
+
+> Kernel hacking ---> Kernel Testing and Coverage ---> Kunit
+> Kernel hacking ---> Rust hacking ---> doctests for `kernel` crate
+
+- qemu will run the tests when booting