daemon purpose

Daemon purpose

You may be wondering what is the --daemon argument (command line) and the Start daemon button (GUI). You are on the right page to know everything you need!

CPU-X UI is intended to run as regular user. However, some data needs root privileges. Here is the daemon's role: do action as root.

Server side

The cpu-x-daemon binary can do following actions:

• read CPU model-specific registers (MSRs) libcpuid reads MSRs to provide following data:
  • CPU minimum multiplier
  • CPU maximum multiplier
  • bus frequency (FSB/BCLK)
  • CPU voltage
  • CPU temperature (Intel CPUs only)
• read DMI table
  dmidecode reads DMI table (from /sys/firmware/dmi/tables/smbios_entry_point or /dev/mem on Linux) to provide following data:
  • motherboard information (manufacturer, model, revision)
  • BIOS information (brand, version, date, ROM size)
  • chipset information (vendor, model)
  • memory information (vendor, model, capacity, speed...)
• access PCI devices (FreeBSD only)
  CPU-X tries to detect PCI devices (from /dev/pci) like:
  • chipset
  • graphic cards
• access DRI devices (Linux only)
  CPU-X tries to read DRI debug data (from /sys/kernel/debug/dri) to provide:
  • GPU monitoring information (AMD GPU with radeon kernel module (prior Graphics Core Next (GCN) family) or NVIDIA GPU with nouveau kernel module)
• load kernel modules
  CPU-X may load kernel modules if required like:
  • MSR module
  • sensors module

Daemon's source code (server side) is available here: https://github.com/TheTumultuousUnicornOfDarkness/CPU-X/blob/master/src/daemon_server.cpp

Client side

The client can start the daemon by using the pkexec command. pkexec command prompts user's password. The PolKit action is io.github.thetumultuousunicornofdarkness.cpu-x-daemon.

Please note that a running PolKit agent is required to use pkexec command (you can refer distro-related documentation about PolKit, e.g. Arch Linux / Gentoo / Ubuntu).

Daemon's source code (client side) is available here: https://github.com/TheTumultuousUnicornOfDarkness/CPU-X/blob/master/src/daemon_client.cpp

Note: you can start the daemon without prompting a password (read Start daemon without asking password).

Communication between clients and server

When the daemon is started (by using --daemon argument on cpu-x command line or by clicking the Start daemon button in the GUI), communication between processes is performed through inter processus communication (IPC). CPU-X uses an Unix domain socket.

Notes: if the daemon is not started, some labels may be empty (read Why some labels are empty?).