How to debug the Linux kernel.
First turn on the following options in .config and recompile:
CONFIG_DEBUG_INFO=y
CONFIG_GDB_SCRIPTS=y
CONFIG_DEBUG_INFO passes -g to GCC.
CONFIG_GDB_SCRIPTS attempts to load handy kernel scripts under scripts/gdb.
You then need to run:
gdb [other options] vmlinux
or from inside GDB:
file vmlinux
to load the debug symbols.
To enable the GDB scripts, you need to allow GDB to auto source the Python script at build-dir/vmlinux-gdb.py, e.g. with:
add-auto-load-safe-path .
This Python file gets sourced because of the naming convention: https://sourceware.org/gdb/onlinedocs/gdb/Python-Auto_002dloading.html
QEMU debugging will not be covered here. See QEMU for more information. It is one of the best methods.
Represents the running kernel memory in core file format!
Usage:
gdb vmlinux /proc/kcore
TODO check: Of course, this only gives multiple static views of the kernel like coredumps, you cannot for example break at a given function with it.
TODO