Ubuntu – How to display messages from kernel module without using dmesg

Building a custom kernel is not necessary

This is my procedure (legacy app, virtualized in vmware player, needing access to parallel port dongle)

in order for the parallel port dongle to work, the Ubuntu user needs to be a member of the lp group. As root (or sudo):

vigr    (add user to group lp)
vigr -s (repeat)

Next, you need to prevent the kernel module lp from loading

1. Edit /etc/modules to ensure lp is not loaded at boot:

   # /etc/modules: kernel modules to load at boot time.
   #
   # This file contains the names of kernel modules that should be loaded
   # at boot time, one per line. Lines beginning with "#" are ignored.
   
   #lp
   rtc
   

2. Blacklist lp module (Ubuntu 10 and later) to allow the player to have access to it.

   Create a file: /etc/modprob.d/blacklist-vmware.conf

   #/etc/modprob.d/blacklist-vmware.conf
   blacklist lp
   

3. Execute the following to update boot image:

   dpkg-reconfigure linux-image-$(uname -r)
   

4. Edit /etc/default/cups to look like this:

   # Cups configure options
   
   # LOAD_LP_MODULE: enable/disable to load "lp" parallel printer driver module
   LOAD_LP_MODULE=no
   

Reboot and test!

lsmod | grep lp

(should be a null response)

Just blacklist the kernel driver:

echo "blacklist usb-storage" | sudo tee -a /etc/modprobe.d/blacklist.conf

After that, nobody can use a USB flash drive in your system.

You'll have to manually "insmod" your driver with sudo to use USB devices again or if you want to restore the initial behaviour remove the module from the blacklist file.