A kernel module that reads the battery and AC plug status and reports them to the Linux kernel as a power supply.

• Reasons for this module
• Usage
  • Prerequisites
  • Compile
  • Loading the module
  • Unloading the module
• Notes

Neither the battery nor the mains plug of that laptop were correctly detected by Linux, since the BIOS provides a (very) broken DSDT. Since I was not able to fix the table, I wrote this kernel module in order to provide the battery information.

See this topic in the Arch Linux forums.

Since this is not an official kernel module you need to compile and load it yourself. Don't worry, it is not complicated.

Note that you need to compile the module on every kernel update!

You need a compiler and the Linux headers for your Kernel version installed.

For pacman based systems:

# pacman -S linux-headers

For APT based systems:

# apt-get install linux-headers-$(uname -r)

It is as simple as cloning the repository and typing "make":

$ git clone https://github.com/jfrimmel/Acer-Switch-Battery-Module.git
$ cd Acer-Switch-Battery-Module
$ make

There shouldn't be any errors and a file "battery-module.ko" (along some others) is created. This is your kernel module.

It can be loaded using the following command:

# insmod battery-module.ko

Note that modprobe is generally a better choice than insmod since modprobe resolves dependencies, but this module has no dependencies and so insmod can be used as well.

If you wish to remove the module at some point you simple execute the following command:

# rmmod battery-module.ko

You don't need to do this under normal circumstances.

If there is a battery detected without this module you should unload the driver for it before loading this kernel module.

Such a driver is most likely the module battery (for ACPI batteries) and ac (for ACPI AC adapters). They could either unloaded using rmmod or blacklisted.

To blacklist those modules execute the following command and reboot:

# echo 'blacklist battery' >> /etc/modprobe.d/blacklist.conf
# echo 'blacklist ac' >> /etc/modprobe.d/blacklist.conf