OpenCV Circle Function Parameters

In Ubuntu 22.04 (Jammy Jellyfish), ModemManager.service still holds significance, though its role and usage scenarios have evolved compared to earlier systems. Below is a detailed analysis:

1. What is ModemManager?

ModemManager (MM) is a system service designed to manage mobile broadband modems (e.g., USB dongles, LTE/5G modems, embedded cellular modules). Its core functions include:

Detecting and initializing modems.
Managing network connections (e.g., APN configuration, dial-up).
Handling modem-related events (e.g., signal strength, SMS).

It interacts with the Linux kernel's usbnet and qmi_wwan drivers, as well as protocols like QMI and MBIM, to enable cellular connectivity on laptops, IoT devices, and servers.

2. Is It Still Relevant in Ubuntu 22.04?

Yes, in the Following Scenarios:

Laptops with Embedded Cellular Modules:
Many modern laptops (e.g., some Dell, HP, or Lenovo models) feature built-in LTE/5G modems. ModemManager is essential for configuring and managing these modules.
USB Mobile Broadband Dongles:
If you use a USB modem (e.g., from carriers like AT&T, Vodafone), MM helps establish connections without manual configuration.
IoT/Gateway Devices:
Systems using cellular modems for headless connectivity (e.g., industrial gateways, Raspberry Pi with LTE hats) rely on MM for automated network management.
Legacy Systems or Specific Modems:
Some older modems or niche devices may still require MM for compatibility with modern Linux kernels.

Less Relevant or Replaced In:

Wi-Fi Hotspots or Standard Wired/Wireless Networks:
For Wi-Fi or Ethernet, Ubuntu uses NetworkManager, which handles these connections natively. ModemManager is unnecessary here.
Modern Systems with Native Support:
Some newer modems (especially those using the ipqmi or sierra drivers) may be directly supported by NetworkManager in Ubuntu 22.04, reducing the need for a separate ModemManager service.
Headless Servers Without Modems:
If your system has no cellular hardware, ModemManager can be safely disabled or removed to reduce resource usage.

3. Default Status in Ubuntu 22.04

Package Installation:
ModemManager is not installed by default on standard Ubuntu desktop or server installations. It is part of the modemmanager package, which must be installed explicitly if needed.
Service Status:
If installed, the service (modemmanager.service) is disabled by default and does not start automatically. You must enable it manually for specific use cases.

4. How to Manage ModemManager in Ubuntu 22.04

Install/Remove:

bash
运行
# Install ModemManager
sudo apt install modemmanager

# Remove ModemManager
sudo apt remove modemmanager

Enable/Disable the Service:

bash
运行
# Enable the service (e.g., for the first time)
sudo systemctl enable --now modemmanager.service

# Disable the service (if no longer needed)
sudo systemctl disable --now modemmanager.service

Check Status:

bash
运行
sudo systemctl status modemmanager.service

5. Alternatives to ModemManager

NetworkManager:
In Ubuntu 22.04, NetworkManager can handle many modern modems via its built-in Mobile Broadband support. Check "Settings > Network > Mobile Broadband" to configure cellular connections directly.
Command-Line Tools:
Tools like mmcli (part of ModemManager) or qmicli can manage modems manually, but this is more advanced and less user-friendly.
Third-Party Utilities:
Some vendors provide proprietary tools for their modems, but these are rare in the Linux ecosystem.

6. When to Use ModemManager vs. NetworkManager

表格

Scenario	Recommendation
Embedded LTE modem in a laptop	Use ModemManager (if needed)
USB dongle with legacy drivers	Use ModemManager
Modern modem with MBIM/QMI support	Prefer NetworkManager
No cellular hardware	Disable/remove ModemManager

Conclusion

In Ubuntu 22.04, ModemManager.service is still meaningful for devices relying on cellular modems, especially older or specialized hardware. However, for most desktop users or systems without mobile broadband needs, it can be safely ignored or removed. Always check your hardware’s compatibility documentation to determine if ModemManager is required.