Bluetooth Stack Architecture

Components

Kobo's Bluetooth implementation consists of three main processes:

Process	Path	Purpose
`mtkbtd-launcher`	`/usr/local/Kobo/`	Launch script for MTK Bluetooth
`mtkbtd`	`/usr/local/Kobo/mtkbtd`	MediaTek Bluetooth daemon
`btservice`	`/usr/bin/btservice`	Bluetooth service (spawned by mtkbtd)

These modules must remain loaded at all times. Unloading them will remove Wi-Fi support, and does not prevent kernel panic on shutdown. Restoration is required to recover Wi-Fi functionality. (See [Known Issues](./05-known-issues.md))

wmt_drv - MediaTek WMT driver (main driver)
wmt_chrdev_wifi - WiFi character device
wmt_cdev_bt - Bluetooth character device
wlan_drv_gen4m - WLAN driver

Checking Loaded Modules

# Verify modules are loaded
lsmod | grep -E "(wmt|wlan|bt)"

# Expected output:
# wlan_drv_gen4m 1908365 0 - Live 0xbf14a000 (O)
# wmt_cdev_bt 16871 0 - Live 0xbf141000 (O)
# wmt_chrdev_wifi 12825 1 wlan_drv_gen4m, Live 0xbf138000 (O)
# wmt_drv 1059215 4 wlan_drv_gen4m,wmt_cdev_bt,wmt_chrdev_wifi, Live 0xbf000000 (O)

D-Bus Services

Kobo uses a custom D-Bus wrapper instead of standard BlueZ interfaces:

Service Name	Purpose
`com.kobo.mtk.bluedroid`	Main Bluetooth service (Kobo's wrapper)
`com.kobo.bluetooth.Agent`	Pairing/authentication agent
`org.bluez`	NOT EXPOSED - use mtk.bluedroid instead

Key Discovery: All D-Bus calls must use com.kobo.mtk.bluedroid as destination, not org.bluez.

D-Bus Service File

Service auto-activation is configured in:

/usr/share/dbus-1/system-services/com.kobo.mtk.bluedroid.service

This allows D-Bus to automatically start mtkbtd-launcher.sh when a method is called on com.kobo.mtk.bluedroid, even if the service isn't running.

Verifying Service Availability

# List available D-Bus services
dbus-send --system --print-reply \
    --dest=org.freedesktop.DBus \
    /org/freedesktop/DBus \
    org.freedesktop.DBus.ListNames | grep -E "(bluez|bluetooth|mtk)"

# Expected output when running:
# string "com.kobo.mtk.bluedroid"
# string "com.kobo.bluetooth.Agent"

# Check if Bluetooth service exists
dbus-send --system --print-reply \
    --dest=org.freedesktop.DBus \
    /org/freedesktop/DBus \
    org.freedesktop.DBus.GetNameOwner \
    string:com.kobo.mtk.bluedroid

Process Verification

# Check if Bluetooth processes are running
ps aux | grep -E "(mtkbtd|btservice)" | grep -v grep

# Expected output when running:
# root      1178  0.0  0.0   1234    567 ?  S  15:18  0:00 {mtkbtd-launcher} /bin/sh /usr/local/Kobo/mtkbtd-launcher.sh
# root      1179  0.0  0.1   2345   1234 ?  Sl 15:18  0:00 /usr/local/Kobo/mtkbtd -skipFontLoad -platform kobo:noscreen --debug
# root      1181  0.0  0.0   1234    567 ?  S  15:18  0:00 /usr/bin/btservice

kobo.koplugin