pikvm/pages/bluetooth_hid.md

Bluetooth HID

Pi-KVM is able to emulate a Bluetooth keyboard & mouse. This is not the main case of using Pi-KVM since you still need it to pair with a remote host, but can be used for something like mobile KVM.

❗ Using Bluetooth HID requires additional configuration of the operating system. For v2, this means losing the UART port, since it will be used by Bluetooth. Also, Bluetooth operation was tested only on RPi4 and v2 platform. Other boards may require different system service settings.

❗ Bluetooth mouse can work only in relative mode. The reason is that many Bluetooth host drivers do not correctly implement HID descriptors. Horizontal scrolling is not supported for the same reason.

Configuring the OS

1. Switch filesystem to RW-mode, perform update and install some packages:

   # rw
   # pacman -Syu
   # pacman -S bluez bluez-utils raspberrypi-bluetooth
   

2. Edit /boot/config.txt and comment these lines:

   #enable_uart=1
   #dtoverlay=disable-bt
   

3. Create an empty directory /var/lib/bluetooth and add mountpoint to /etc/fstab:

   # mkdir /var/lib/bluetooth
   # echo 'tmpfs /var/lib/bluetooth tmpfs nodev,nosuid,mode=0755 0 0' >> /etc/fstab
   

4. Override and enable the services:

   # mkdir /etc/systemd/system/bluetooth.service.d
   # cat << EOF > /etc/systemd/system/bluetooth.service.d/override.conf
   [Service]
   ExecStart=
   ExecStart=/usr/lib/bluetooth/bluetoothd --noplugin=*
   EOF
   # systemctl enable bluetooth
   # systemctl enable raspberrypi-btuart
   

5. Override kvmd service:

   # mkdir /etc/systemd/system/kvmd.service.d
   # cat << EOF > /etc/systemd/system/kvmd.service.d/override.conf
   [Service]
   AmbientCapabilities=CAP_NET_RAW CAP_NET_BIND_SERVICE CAP_SYS_ADMIN CAP_SETUID CAP_SETGID CAP_CHOWN
   CapabilityBoundingSet=CAP_NET_RAW CAP_NET_BIND_SERVICE CAP_SYS_ADMIN CAP_SETUID CAP_SETGID CAP_CHOWN
   EOF
   

6. Add following lines to /etc/kvmd/override.yaml:

   kvmd:
       hid:
           type: bt
   

7. Perform reboot: reboot.
8. To reverse, uncomment lines from Step 2 and remove lines in Step 6, reboot

Using Bluetooth HID

• After a reboot, the Pi-KVM will be ready for detection and pairing with no auth. You will see the Pi-KVM HID device.
• Once the server is connected, Pi-KVM will no longer be discoverable and pairable to other clients until you unpair the server.
• If something went wrong, use the web menu System -> Reset keyboard & mouse. This will cause unpair the device and switch the Pi-KVM to public mode before the first client is connected.