Kernel

The Linux kernel user’s and administrator’s guide

• query CPU information: cpuid
• show system/kernel info: uname -a
• show (or configure) kernel parameters at runtime: sysctl -a
• show kernel memory usage: free
• show modules loaded: lsmod
• show all module parameters: modinfo -p <modname>
• show current module parameters: systool -m <modname> -av

• show kernel (boot) messages: dmesg
• configure to show more kernel messages (with timestamp)

  echo 8 > /proc/sys/kernel/printk
  echo Y > /sys/module/printk/parameters/time

  or use for example loglevel=7 as kernel boot parameter (as recommended at StackOverflow).

• Ubuntuusers Wiki: udev
• ArchWiki: udev
• Daniel Drake: Writing udev rules
• Stack Exchange: Automount USB sticks on Gentoo

• show udev daemon¹⁾ events: udevadm monitor --environment
• after changing udev rules: udevadm control --reload

• /etc/udev/rules.d, /lib/udev/rules.d: udev rules

• show all block devices: lsblk
• show hard drive information: hdparm -I /dev/sda
• blacklist the UAS driver for LaCie USB mass storage in file /etc/modprobe.d/usb-storage-quirks.conf:²⁾

  # Do not use USB driver UAS (USB Attached SCSI) with LaCie mass storage.
  # This is a younger USB 3.x protocol and not stable at the moment.
  # See usb-storage.quirks in https://www.kernel.org/doc/Documentation/admin-guide/kernel-parameters.txt
  options usb-storage quirks=059f:105e:u

• Super User: What is the Linux command to find out hardware info?
• Pratham Patel: Get All Kind of System Information in Linux Terminal With inxi

• show PCI information: lspci -k -nn

• show tree of USB devices: lsusb -t

• ArchWiki: Bluetooth
• ArchWiki: Bluetooth keyboard
• ArchWiki: Bluetooth mouse
• ArchWiki: Bluetooth - Pairing
• BITblokes (JDO): MX Keys Mini (Logitech) mit Linux verbinden – gute Tastatur, ABER

Checklist:

1. check kernel module btusb is load and running: lsmod | grep btusb
2. check for kernel problems: dmesg | grep -i bluetooth
3. check Bluetooth status: sudo systemctl status bluetooth, or sudo service bluetooth status
4. after changing files in /etc/bluetooth do: sudo service bluetooth restart
5. use sudo bluetoothctl to check for Bluetooth devices and their state (also the Blueman applet might be useful for this)
6. check Laptop Power Management for Bluetooth status: sudo tlp-stat -u -v
7. change /etc/default/tlp to adjust Laptop Power Management regarding Bluetooth:
   • TLP Settings
   • TLP FAQ