# Linux Kernel Module Cheat

##### 17.6.1.5. Panic trace show addresses instead of symbols

If `CONFIG_KALLSYMS=n`, then addresses are shown on traces instead of symbol plus offset.

In v4.16 it does not seem possible to configure that at runtime. GDB step debugging with:

    ./run --eval-after 'insmod dump_stack.ko' --gdb-wait --tmux-args dump_stack

shows that traces are printed at `arch/x86/kernel/dumpstack.c`:

    static void printk_stack_address(unsigned long address, int reliable,
                     char *log_lvl)
    {
        touch_nmi_watchdog();
        printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
    }

and `%pB` is documented at `Documentation/core-api/printk-formats.rst`:

    If KALLSYMS are disabled then the symbol address is printed instead.

I wasn’t able do disable `CONFIG_KALLSYMS` to test this this out however, it is being selected by some other option? But I then used `make menuconfig` to see which options select it, and they were all off…​