How

sudo apt install git dkms

Clone this repo and go into the source code directory:

git clone https://github.com/free5lot/hid-apple-patched
cd hid-apple-patched

Install module:

sudo dkms add .
sudo dkms build hid-apple/1.0
sudo dkms install hid-apple/1.0

Then, create file /etc/modprobe.d/hid_apple.conf. The following configuration emulates a standard PC layout:

options hid_apple fnmode=2
options hid_apple swap_fn_leftctrl=1
options hid_apple swap_opt_cmd=1
options hid_apple rightalt_as_rightctrl=1
options hid_apple ejectcd_as_delete=1

Finally, apply the new config file:

sudo update-initramfs -u

To (re-)load the module for immediate use, run

sudo modprobe -r hid_apple; sudo modprobe hid_apple

in one go (since the first command will disable your Apple keyboard). Alternatively, run sudo reboot, and the new module should be loaded on reboot.

Configuration

Permanent configuration is done in file /etc/modprobe.d/hid_apple.conf. The format is one option-value pair per line, like swap_fn_leftctrl=1. After writing to the file, do sudo update-initramfs -u and reboot. Temporary configuration (applies immediately but is lost after rebooting) is possible by writing to virtual files in /sys/module/hid_apple/parameters/, like echo 1 | sudo tee /sys/module/hid_apple/parameters/swap_fn_leftctrl.

These options are from the original mainstream hid-apple module:

• fnmode - Mode of top-row keys
  • 0 = disabled
  • 1 = normally media keys, switchable to function keys by holding Fn key (Default)
  • 2 = normally function keys, switchable to media keys by holding Fn key
• swap_opt_cmd - Swap the Option ("Alt") and Command ("Flag") keys
  • 0 = as silkscreened, Mac layout (Default)
  • 1 = swapped, PC layout
• swap_fn_leftctrl - Swap the Fn and left Control keys
  • 0 = as silkscreened, Mac layout (Default)
  • 1 = swapped, PC layout
• iso_layout - Enable/Disable hardcoded ISO-layout of the keyboard. Possibly relevant for international keyboard layouts
  • 0 = disabled,
  • 1 = enabled (Default)

And these options were added in the patched version:

• rightalt_as_rightctrl - Use the right Alt key as a right Ctrl key
  • 0 = as silkscreened, Mac layout (Default)
  • 1 = swapped, PC layout
• ejectcd_as_delete - Use Eject-CD key as Delete key, if available
  • 0 = disabled (Default)
  • 1 = enabled
• lock_as_delete - Use Lock key as Delete key, if available
  • 0 = disabled (Default)
  • 1 = enabled
• swap_fn_f13_insert - Swap the Fn and f13 keys, making Fn Insert and f13 Fn. For people who need Insert
  • 0 = disabled (Default),
  • 1 = enabled

Note: swap_fn_f13_insert will be ignored if swap_fn_leftctrl is activated.

Warning regarding Secure Boot (on non-Apple computers)

Some distributions, including Ubuntu 16.04, require that all modules are signed if Secure Boot is enabled. This breaks all third-party modules. There are various work-arounds, the easiest of which is to disable secure boot. This is currently not an issue on Apple computers, because Apple firmware does not support Secure Boot. See issue #23.

Links and mentions

• ArchWiki (documentation wiki of Arch Linux) - Apple Keyboard - Swap the Fn key and Left Ctrl key (added by @Aetf)).
• Official documentation of openSUSE - Installation on a Mac (added by Cornertwist)
• Official documentation of Ubuntu - AppleKeyboard - Mapping keys (added by @Aetf).