Boot Arguments

Boot arguments configure various aspects of the kernels behaviour. They read from the /chosen/bootargs property of the flattened device tree that is passed to the kernel by the previous stage bootloader.

The format is a simple key=value;key=value;.. list of semicolon separated of key-value pairs.

log

Allows configuring the verbosity and filtering of debug messages.

# Enable the most verbose logging messages
just run //sys:k23-qemu-riscv64 -- --append "log=trace"
# A more reasonable configuration that keeps trace messages enabled, but silences the very spammy ones
just run //sys:k23-qemu-riscv64 -- --append "log=trace,cranelift_codegen=off,sharded_slab=off"

The underlying buck2 invocation is buck2 run //sys:k23-qemu-riscv64 -- --append "..."; everything after -- is forwarded to QEMU.

backtrace

Allows configuring the verbosity of kernel panic backtraces. There are two possible values: short (default) and full. short will print an abridged backtrace that omits frames related to the unwinding and panic machinery itself.

# To print shorter panic backtraces (the default)
just run //sys:k23-qemu-riscv64 -- --append "backtrace=short"
# To print more verbose panic backtraces
just run //sys:k23-qemu-riscv64 -- --append "backtrace=full"