Dynamic USB configuration¶
PiKVM emulates a number of USB devices to ensure normal operation: keyboards, mouse and mass storage drive. Also an additional relative mouse may be present (like on PiKVM V4 by default), or a user configured USB Ethernet or Serial port.
In rare cases, the host BIOS/UEFI may not understand such a large number of emulated devices on single USB port, so some of them may need to be disabled. USB reconfiguration usually requires a reboot, but it is possible to temporarily disable already configured existing emulated devices.
This feature is experimental. Due to the imperfections of the kernel modules, rarely a dynamic configuration change can lead to a kernel panic and reboot.
For PiKVM V3 and V4 this is considered more secure because they have two independent watchdog systems that can bring devices back to life after a timeout of a few minutes.
kvmd-otgconf utility allows you to view and modify the USB configuration on the fly.
It requires root permission and can be used for example from a web terminal.
View the config:
# kvmd-otgconf + hid.usb0 # Keyboard + hid.usb1 # Absolute Mouse + hid.usb2 # Relative Mouse + mass_storage.usb0 # Mass Storage Drive
Disabling the device:
[root@pikvm ~]# kvmd-otgconf --disable-function mass_storage.usb0 + hid.usb0 # Keyboard + hid.usb1 # Absolute Mouse + hid.usb2 # Relative Mouse - mass_storage.usb0 # Mass Storage Drive
Enabling the device:
[root@pikvm ~]# kvmd-otgconf --enable-function mass_storage.usb0 + hid.usb0 # Keyboard + hid.usb1 # Absolute Mouse + hid.usb2 # Relative Mouse + mass_storage.usb0 # Mass Storage Drive
Web UI menu¶
Using the pseudo-GPIO driver, you can also control devices via the menu in the web interface. Read about GPIO basics here.
To setup the menu, use
kvmd-otgconf --make-gpio-config to generate the configuration, and merge it
with your existing one in
/etc/kvmd/override.yaml in a usual way.
The example of
kvmd-otgconf --make-gpio-config output
# kvmd-otgconf --make-gpio-config kvmd: gpio: drivers: otgconf: type: otgconf scheme: hid.usb0: driver: otgconf mode: output pin: hid.usb0 pulse: false hid.usb1: driver: otgconf mode: output pin: hid.usb1 pulse: false hid.usb2: driver: otgconf mode: output pin: hid.usb2 pulse: false mass_storage.usb0: driver: otgconf mode: output pin: mass_storage.usb0 pulse: false view: table: - ["#Keyboard", "#hid.usb0", hid.usb0] - ["#Absolute Mouse", "#hid.usb1", hid.usb1] - ["#Relative Mouse", "#hid.usb2", hid.usb2] - ["#Mass Storage Drive", "#mass_storage.usb0", mass_storage.usb0]