108 lines
No EOL
2.2 KiB
Markdown
108 lines
No EOL
2.2 KiB
Markdown
## Setup env
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On NixOS:
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- Ensure Linux Kernel is the same as you configuration.
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Use this command to update nix inputs
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```bash
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nix flake update --override-input nixpkgs "github:NixOS/nixpkgs/$(nixos-version --revision)"
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```
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- Use direnv allow or nix develop to setup shell.
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On other distros:
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1. With direnv, in .envrc, change line by `use flake .#other`
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2. With nix only, use `nix develop .#other`
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3. Otherwise, you need to setup LINUX_MODULES_FOLDER to linux modules folder of your distro (ex: `/lib/modules/$(uname -r)`) in your shell (ex: .bashrc)
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## make : targets list
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- all : Compiling kernel (by default)
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- clean : Cleaning build folder
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All subfolder is configured to use LINUX_MODULES_FOLDER env variable set by flake develop
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## How test module
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Step 1: Load module
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```bash
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sudo insmod [module_name].ko
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```
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**Warning**: Can fail if secure boot is enabled (see notes about secure boot in below)
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Step 2: Check logs
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```bash
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sudo dmesg | tail
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```
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Step 3: Unload module
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```bash
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sudo rmmod [module_name].ko
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```
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## Usefull links
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- https://www.kernel.org/doc/html/latest/
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- https://elixir.bootlin.com/linux/v6.13/source/
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- https://static.lwn.net/images/pdf/LDD3/ch01.pdf
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- https://sysprog21.github.io/lkmpg
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## Notes
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### Find required headers files
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```
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nix shell nixpkgs#bear
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cd 01_basic_module/
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bear --append --output ../.vscode/compile_commands.json -- make -C $LINUX_MODULES_FOLDER/build M=$PWD modules
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```
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Search -I args and -D args
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### Sign kernel module for testing with secure boot enabled
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Prerequisites: Own secure boot keys configured.
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Secure boot keys can be found in :
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- Fedora : `/etc/pki/akmods`
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- With sbctl : `/var/lib/sbctl`
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```
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sign-file sha256 $SECUREBOOT_KEYS_PATH/private_key.priv $SECUREBOOT_KEYS_PATH/public_key.der <module_file>.ko
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```
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sign-file executable is in `/usr/src/kernels/$(uname -r)/scripts`
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Full example (run as root):
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1. Fedora
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```bash
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/usr/src/kernels/$(uname -r)/scripts/sign-file sha256 /etc/pki/akmods/private/private_key.priv /etc/pki/akmods/certs/public_key.der <module_file>.ko
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```
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### Format
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1. .clang-format
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How update .clang-format
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```bash
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curl https://raw.githubusercontent.com/torvalds/linux/refs/heads/master/.clang-format -o .clang-format
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```
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Format files
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```bash
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clang-format -i **/*.c
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``` |