Crate printk

A standalone, #![no_std]-friendly Logger crate. Based on the design of the logger built into the bootloader crate and meant to be used in OS kernels.

To use this crate, specify it as a dependency in your kernel’s Cargo.toml, then initialize it.

Initialization

The logger needs to be initialized in order to be used. To do that, one must first create a global instance, using a crate like conquer_once:

pub static PRINTK: OnceCell<LockedPrintk> = OnceCell::uninit();

After this, the log crate needs to be attached to it. This requires the following 3 steps:

1. Use the get_or_init method to unwrap the LockedPrintk object from its outer OnceCell
2. Use log::set_logger to tell the log crate what to attach to
3. Use log::set_max_level to tell the log crate how many levels of logging you want to do

Here’s an example function demonstrating how this is done in pure Rust:

pub fn printk_init(buffer: &'static mut [u8], info: FrameBufferInfo) {
    let kernel_logger = printk::PRINTK.get_or_init(move || printk::LockedPrintk::new(buffer, info));
    log::set_logger(kernel_logger).expect("logger already set");
    log::set_max_level(log::LevelFilter::Trace);
    log::info!("Hello, Kernel!");
}

Contributing

If you have any functionality to add, feel free to create a pull request. I’ll gladly test and accept it. If you have any bugs to report, that is also what GitHub is for. Also, if you’re an employer in the Mission Viejo, California area, feel free to reach out to me on Indeed. I’ve got push notifications set up there, so any message you send through Indeed will definitely be seen.

Example output

Structs

LockedPrintk

Memory safety: need to ensure that each instance is mutexed

Printk

Structure to render characters to the framebuffer