Install on Linux

pcu runs on 64-bit Linux. A bundled setup script installs the binaries and configures unprivileged access to the vehicle PC’s SMBus, so the app and CLI run as a normal desktop program without root. pcu is developed and tested on Ubuntu 24.04, but the script is distribution-agnostic.

Requirements

• A 64-bit Linux system. pcu is developed and tested on Ubuntu 24.04 LTS.
• Root access (sudo) to run the setup script.
• No .NET runtime to install. pcu ships as self-contained binaries.

Note

Need pcu tested on a different distribution or kernel? Contact In-CarPC support and tell us what you are running. We can usually accommodate it.

Install pcu

In-CarPC machines shipped with Linux do not come with pcu preinstalled as of July 2026. We plan to provision it by default soon; until then, contact In-CarPC support and we will send you the Linux build. It is a .tar.gz archive.

1. Extract the archive and open a terminal in the extracted folder. It contains pcu, pcu-cli, and pcu-setup.sh.
2. Run the setup script as root:

$ sudo bash pcu-setup.sh install

The installer:

• copies pcu and pcu-cli to /opt/pcu
• creates the i2c group and a udev rule (/etc/udev/rules.d/90-pcu-i2c.rules) that gives that group read/write access to /dev/i2c-*
• loads the i2c-dev kernel module at every boot (/etc/modules-load.d/pcu-i2c.conf)
• adds your user to the i2c group
• installs a desktop entry so pcu appears in your application launcher
• symlinks pcu-cli into /usr/local/bin so it is on your PATH
• optionally grants CAP_SYS_RAWIO for CQ40 digital I/O (it prompts, and defaults to No)

3. Log out and back in so your new i2c group membership takes effect. For a CLI-only session in the current shell, newgrp i2c also works.
4. Start pcu from your application launcher (search for “pcu”), or run /opt/pcu/pcu. The CLI is available as pcu-cli.

Caution

Treat the i2c group as privileged on a deployed vehicle PC: members can drive the MCU’s power-sequencing registers directly. Don’t add untrusted users.

Verify the installation

The setup script includes a read-only health check (“doctor”). It needs no root. From the folder you extracted, run:

$ bash pcu-setup.sh status
==> Installation
  [ OK ] Binaries installed in /opt/pcu
  [ OK ] CLI on PATH (/usr/local/bin/pcu-cli)
  [ OK ] Desktop entry present
  [ OK ] Icon installed

==> SMBus access (i2c)
  [ OK ] udev rule present
  [ OK ] modules-load drop-in present
  [ OK ] i2c-dev module loaded
  [ OK ] Found 2 /dev/i2c-* node(s)
  [ OK ] Nodes group 'i2c' (mode 660)
  [ OK ] Intel I801 SMBus adapter detected

==> Port I/O access (CQ40, optional)
  [ OK ] /dev/port present
  No CAP_SYS_RAWIO set -- CQ40 GPIO needs sudo, or grant it: sudo bash pcu-setup.sh caps

==> Group membership
  [ OK ] Group 'i2c' exists
  [ OK ] User 'youruser' is in 'i2c'
  [ OK ] Membership active in this session

All checks passed.

The doctor exits 0 when everything passes, 1 if there are warnings, and 2 if it finds problems, so you can use it in scripts.

Then confirm pcu can reach the MCU with pcu-cli status:

$ pcu-cli status
pcu v1.0.0  - In-CarPC CQ20 Status
----------------------------------------
  Platform            : In-CarPC CQ20 (Intel Atom x6425E)
  MCU Identity        : CQ20 MCU
  Hardware Rev        : DTB-IGN-MCU VER:10
  Firmware            : 12

  MCU Firmware        : 12
  Ignition Mode       : On
  Anti-Crank Delay    : 6s           anti-crank filter before DC power
  Boot Delay          : 4s           DC rails stable before power button
  Shutdown Delay      : 5m           IGN off to ACPI shutdown command
  Force Off Timeout   : 2m           hard power cut if OS hangs

CQ40 series: digital I/O access

CQ40 digital I/O uses raw x86 port I/O through /dev/port, which the kernel gates behind the CAP_SYS_RAWIO capability rather than file permissions. You have two options:

• Run pcu-cli under sudo. The GUI cannot use this route: it does not self-elevate under Wayland.
• Grant the capability once, so both the GUI and CLI can use CQ40 digital I/O without sudo:

$ sudo bash pcu-setup.sh caps

Caution

CAP_SYS_RAWIO grants unrestricted access to all I/O ports and physical memory, which is effectively root-level hardware access, a larger trade-off than the i2c group. It is opt-in and never applied silently. Only a CQ40 (port-I/O) machine needs it; a CQ20 (SMBus) machine does not.

On a system with Secure Boot enabled, kernel lockdown can block /dev/port even for root, so CAP_SYS_RAWIO may not be enough. See Linux Issues.

File capabilities live on the binary and are lost whenever it is replaced, so re-run sudo bash pcu-setup.sh caps after every pcu update, or use repair, which re-applies the configuration and preserves a prior capability grant.

Note

CQ40 series support on Linux is not yet validated. See Supported Platforms.

The pcu-setup.sh commands

Run the script again from the extracted release folder for any of these. status needs no root; the others re-run themselves with sudo when required.

Command	What it does
install	Install or update pcu and set up i2c-group SMBus access. Add --with-portio to also grant CAP_SYS_RAWIO for CQ40 digital I/O.
status	Show install and hardware-access health. No root needed. Exit 0 (ok), 1 (warnings), 2 (problems).
repair	Re-apply the i2c setup without a full reinstall. Preserves a prior CAP_SYS_RAWIO grant.
caps	Grant CAP_SYS_RAWIO so CQ40 digital I/O (/dev/port) works without sudo.
uninstall	Remove pcu. Keeps the shared i2c group, the i2c-dev module, and group membership. Add --yes to skip the confirmation prompt.
version	Show the installed pcu version.
help	Show the command list.

Run the script with no command in a terminal for an interactive menu.

Updating pcu

To update, extract the new release and run the installer again:

$ sudo bash pcu-setup.sh install

It replaces the binaries in /opt/pcu and re-applies the configuration. If you had granted CAP_SYS_RAWIO for CQ40 digital I/O, re-grant it afterwards with sudo bash pcu-setup.sh caps (file capabilities reset when a binary is replaced), or run sudo bash pcu-setup.sh repair, which preserves the previous grant.

Tip

pcu-cli does everything the GUI does from the command line, for scripting and remote sessions. See the Command Reference.