How to disable pesky drivers/module loading w/o kernel recompile in Debian [updated]

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[Hi faithful readers. You might or might not know that I am somewhat a computer nerd, going back to junior high when I built a computer (and installed Redhat Linux 5.2!) with my brother. I have decided to finally begin documenting some of the more difficult and obscure things I figure out in computer-land, since they are generally difficult because no coherent documentation or guidance is to be found...]

The method for disabling the loading of specific modules is at the bottom of this post.

The scenario: I have an IBM ThinkPad X30 which has an Intersil Prism 2.5 chipset for wireless networking. The firmware is a revision which has support for WPA2 security. The process of updating the firmware to this revision was somewhat of an ordeal which I hopefully will document later. This wireless chipset is somewhat unique in that the Linux kernel has two different drivers which support it, orinoco (implicated by the hermes module) and hostap. The orinoco driver, however, doesn’t support WPA2 encryption. Guess which driver loads first by default in my Debian Etch (4.0) setup and precludes the other from working? Yes, the less functional orinoco driver.

Since for various reasons I require WPA2 encryption from time to time, I had to find a way to make the hostap driver load first. Of course, I could always recompile the kernel and exclude the orinoco driver, but this becomes tedious every time Debian security releases a patched kernel. Plus, it’s time-consuming, and isn’t the point of a modular kernel to make it possible to add and remove the modules you want without recompiling?

So after attempts with /etc/modprobe.d/blacklist and other obvious methods of preventing modules from loading which didn’t work [I should retrace my steps and document the failed methods better, I am sorry], I found the right method on an online forum. I am posting it here hoping it might be easier for those in a similar situation to find.

(As root) create a file named

/etc/modprobe.d/00local

Edit the file to contain the following text:

install hermes /bin/true
install orinoco /bin/true
install orinoco_pci /bin/true

Replace “hermes,” “orinoco,” etc. with whatever modules you are hoping to prevent from loading.

You can list as many or as few modules as you need in the 00local file.

The program /bin/true is a program to “do nothing, successfully” according to the manpage (man true). So this method somehow changes what command is run when a process prompts the loading of a module from <modprobe modulename> to </bin/true>, thus doing nothing, instead of loading the module you never wanted. Beautiful. According to this discussion:http://www.cyberciti.biz/tips/avoid-linux-kernel-module-driver-autoloading.html, where I found this method, it works for Fedora 7 at least. Not sure about other distributions. I confirm it works for Debian etch (4.0). This means it might work for Ubuntu as well.

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Tags: computers, debian, etch, hostap, IBM X30, kernel, linux, modprobe, modules, orinoco, prism 2.5, WPA2