kernel - bunnyamin/bunnix GitHub Wiki

Parameters

Current running kernel parameter configuration

  • zgrep CONFIG_NFS_FS= /proc/config.gz -> CONFIG_NFS_FS=y

Debug

Command Example
Kernel release $ uname -r -> 4.17.4-1-ARCH
Error Cause Consequence Remedy
ACPI Error: Needed type [Reference], found [Integer] ffff909a64f14048 (20170531/exresop-103)
ACPI Exception: AE_AML_OPERAND_TYPE, While resolving operands for [OpcodeName unavailable] (20170531/dswexec-461)
ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550)
 outdated BIOS, incompatibility issue (1) update BIOS (2) adjust kernel parameters; acpi=off may have unintended consequences, for example ASUS u500vz ch08m the keyboard ceased to function.
Cannot switch tty (ctrl+alt+f[1-6]) Ensure user root has permission 755 on root /.
EXT4-fs (sdc4): Delayed block allocation failed for inode 47189317 at logical offset 1132 with max blocks 4 with error 121
EXT4-fs (sdc4): This should not happen!! Data will be lost 		"This message means that data in memory will not be written to disk; we do not consider that grave unless the failure is silent." Ben Hutchings, email reply to Gilberto Segundo (Sat, 02 Oct 2010 00:05:32 +0100) The corrupted inode is each time /var/log/journal/fcf64750dde34b52afe85358b303af52/system.journal and smartctl (Extended/long test) reports no errors: find / -inum <INODE> -print and delete file.
kauditd_printk_skb: 10 callbacks suppressed Role of “kauditd_printk_skb” in linux kernel

Kernel messages

Disable unsolicited kernel messages except emergency (Panic):

  • dmesg -n 1

Modules

Is the devices is controlled by hardware (hard) or a program (soft): rfkill list. If the device is

  • "hard-blocked" then it can only be unblocked with the hardware interface, for example a button or switch
  • "soft-blocked" then it can be unblocked with the command rfkill unblocked <device>.
0: sunxi-bt: Bluetooth
        Soft blocked: no
        Hard blocked: no
1: bluetooth: Bluetooth
        Soft blocked: no
        Hard blocked: no
2: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no
3: hci0: Bluetooth
        Soft blocked: no
        Hard blocked: no

Kernel mode settings

KMS (kernel mode settings)

  • module_name.parameter_name=parameter_value

video=HDMI-A-1:1024x768@85

Test status of display connection:

  • cat /sys/class/drm/card1-HDMI-A-1/status

List modules

  • modprobe -c

Load module

Temporarily

  • insmod /path/to/module.ko

Permanently

  • echo 'module' > /etc/modules-load.d/name.conf

Block modules

  • /etc/modprobe.d/blacklist.conf

Prevent a module from being loaded either as:

  • blacklist <module> The module could still be loaded as a dependency of another module that is not blacklisted.
  • install <module> /bin/true

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