After installing Ubuntu on an old Dell laptop to replace Windows 7, I’ve noticed the WiFi LED indicator kept blinking all the time which is quite annoying. That reminded me a couple year ago when I switched on winter tires for the first time on my car, the tire pressure warning light turned on because they don’t have pressure sensors. I went back to the garage to see if they could have a solution and the technician told me that either I needed to get TPM installed with extra cost or I had to live with that. He said most of people would just use something (like an expired credit card) to cover it — the problem doesn’t exist if you don’t see it!
So I googled the LED blinking issue and it’s interesting that I did see people suggesting to use a small piece black paper to cover it!
Fortunately it’s a technical issue which just needed a small configuration change for Intel WiFi chipset which supports module options to control the behaviour.
First I used “lsmod|grep -i wi” to see which WiFi module is loaded in the Kernel.
lsmod |grep -i wi
I saw the module name “iwlwifi” returned. With that information, I checked what parameter the module supports:
root@joe-computer:/etc/modprobe.d# modinfo iwlwifi|grep parm |grep led parm: led_mode:0=system default, 1=On(RF On)/Off(RF Off), 2=blinking, 3=Off (default: 0) (int)
Then I created a configuration file under /etc/modprobe.d/ — could be any name with the file extension “.conf“. It is just like how normal configuration directory works on Linux, modprobe reads configuration files with the extension “.conf” one by one under this directory and apply settings. In the file I gave:
options iwlwifi led_mode=1
Here it followed the format “command module options“. So options is a modeprobd command, iwlwifi is the module name and the actual option is “led_mode=1“. When modeprob reads this file, it directs the module iwlwifi to keep the LED light on. Rebooted the laptop and I got a steady blue light!
For more information (such as commands) about modeprob.d, check the man page:
man 5 modeprob.d