## How to code kernel modules for DF 


* Main kernel directory: /usr/src/sys/kern


* General coding guidelines: man style

### Example: Loading a module 
    
    cd /usr/src/sys/vfs/portal
    # build module
    make
    
    # load module
    kldload portal
    # look at module footprint
    kldstat
    
    # alter source code
    make clean
    make
    lsvfs
    
    # unload module
    kldunload
    # look at module footprint
    kldstat
    lsvfs



### Important functions 

* kprintf("Message, displayed in dmesg");

### TODO 
How can you see the debug output of a module?

How can you redirect the debug output to dmesg?

Which debug output facility you should use (not dmesg?) to look at messages from a module?