Kernel Modules

System 2026-04-28

Kernel modules are loadable drivers and extensions that the Linux kernel can load and unload at runtime without rebooting. On Shani OS, module configuration files placed in /etc/modules-load.d/ and /etc/modprobe.d/ live in the /etc overlay and persist across all OS updates and rollbacks.

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Listing and Inspecting Modules

# List all currently loaded modules
lsmod

# Show information about a module (description, parameters, dependencies)
modinfo kvm
modinfo iwlwifi
modinfo nvidia

# Show only specific fields
modinfo -F filename kvm        # path to the .ko file
modinfo -F parm kvm            # available parameters
modinfo -F depends kvm         # dependencies

# Check if a module is loaded
lsmod | grep kvm

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Loading and Unloading Modules

# Load a module (for the current session only)
sudo modprobe kvm
sudo modprobe kvm_intel          # or kvm_amd depending on CPU

# Load with parameters
sudo modprobe iwlwifi 11n_disable=1
sudo modprobe usbcore autosuspend=1

# Unload a module
sudo modprobe -r kvm_intel
sudo rmmod kvm_intel             # alternative, does not handle dependencies

# Unload a module and all its dependents
sudo modprobe -r --remove-dependencies kvm_intel

# Dry run — show what would be loaded/unloaded
sudo modprobe --dry-run kvm

⚠️ rmmod fails if the module is in use. Use modprobe -r which handles the dependency chain, or check what is using it with lsmod | grep <module> and look at the "Used by" column.

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Persistent Module Loading

To load a module automatically at boot, create a file in /etc/modules-load.d/. Files here are processed by systemd-modules-load.service early in the boot sequence.

# Load a single module at boot
echo "kvm_intel" | sudo tee /etc/modules-load.d/kvm.conf

# Load multiple modules
sudo tee /etc/modules-load.d/virtualisation.conf << 'EOF'
kvm
kvm_intel
vhost_net
EOF

Each file should contain one module name per line. Comments starting with # are ignored.

# Verify the service loaded all modules correctly
systemctl status systemd-modules-load.service
journalctl -u systemd-modules-load.service

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Module Parameters

Module parameters can be set persistently in /etc/modprobe.d/.

# Disable 802.11n (workaround for some Wi-Fi issues)
echo "options iwlwifi 11n_disable=1" | sudo tee /etc/modprobe.d/iwlwifi.conf

# Set KVM nested virtualisation
echo "options kvm_intel nested=1" | sudo tee /etc/modprobe.d/kvm.conf
echo "options kvm_amd nested=1"   | sudo tee /etc/modprobe.d/kvm.conf   # AMD

# Set USB autosuspend delay
echo "options usbcore autosuspend=5" | sudo tee /etc/modprobe.d/usb.conf

# Verify active parameters for a loaded module
cat /sys/module/kvm_intel/parameters/nested
cat /sys/module/iwlwifi/parameters/11n_disable

Changes to /etc/modprobe.d/ take effect on the next module load. To apply immediately: unload and reload the module with modprobe -r then modprobe.

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Blacklisting Modules

Blacklisting prevents a module from loading automatically. Useful for disabling a buggy driver, forcing a different driver, or preventing a conflicting module from loading alongside another.

# Blacklist a module
echo "blacklist nouveau" | sudo tee /etc/modprobe.d/blacklist-nouveau.conf

# Blacklist and also prevent loading as a dependency
sudo tee /etc/modprobe.d/blacklist-nouveau.conf << 'EOF'
blacklist nouveau
install nouveau /bin/false
EOF

The install <module> /bin/false directive is stronger — it replaces the module's install command with /bin/false, preventing it from loading even as a dependency of another module.

# Verify a module is blacklisted
cat /etc/modprobe.d/*.conf | grep blacklist

💡 Common blacklisting use cases on Shani OS: disabling nouveau when using the NVIDIA proprietary driver, blacklisting pcspkr to silence the PC speaker beep, or blacklisting iTCO_wdt to prevent false watchdog triggers.

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Module Aliases

Aliases let you refer to a module by a friendly name or map a hardware ID to a driver.

# Show all aliases for a module
modinfo -F alias kvm_intel

# Show which module would handle a specific hardware ID
modprobe --show-depends pci:v00008086d00001234sv...

# List all alias mappings (from modules.alias in the kernel)
cat /lib/modules/$(uname -r)/modules.alias | grep iwlwifi

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Dracut and the Initramfs

On Shani OS, the initramfs is built with dracut. Modules that must be available before the root filesystem is mounted (e.g. storage controllers, crypto drivers) need to be included in the initramfs.

# Force-include a module in the initramfs
echo "add_drivers+=\" virtio_blk virtio_scsi \"" | sudo tee /etc/dracut.conf.d/virtio.conf

# Regenerate the initramfs after changes
sudo dracut --force

# Verify a module is present in the initramfs
lsinitrd | grep virtio
lsinitrd /boot/initramfs-linux.img | grep <module>

⚠️ After adding or changing module configuration that affects early boot (storage, crypto, firmware), always regenerate the initramfs with sudo dracut --force and reboot to verify the new initramfs works before removing the previous boot slot.

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Firmware

Many modules require firmware blobs that are loaded from /lib/firmware/. Shani OS ships a comprehensive linux-firmware package split by vendor. If a module reports a missing firmware file:

# Check dmesg for firmware load failures
dmesg | grep -i firmware
dmesg | grep "Direct firmware load"

# List available firmware files for a driver
ls /lib/firmware/iwlwifi*         # Intel Wi-Fi firmware
ls /lib/firmware/amdgpu/          # AMD GPU firmware

# Check which firmware package provides a file
pacman -F /lib/firmware/iwlwifi-8265-36.ucode

If a firmware file is genuinely missing, the relevant linux-firmware-<vendor> package may not be installed. On Shani OS these are split packages (e.g. linux-firmware-intel, linux-firmware-amdgpu).

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Useful Diagnostics

# Show kernel messages related to module loading since boot
dmesg | grep -E "module|driver|firmware" | head -40

# Show all modules and their memory usage
lsmod | sort -k2 -rh

# Find which module handles a device (by PCI ID)
lspci -k | grep -A3 "VGA\|Network\|Audio"

# Find which module handles a USB device
lsusb -v 2>/dev/null | grep -E "idVendor|idProduct|Kernel driver"

# Check for module load errors at boot
journalctl -b | grep -i "module\|modprobe\|failed to load"

# Show all loaded modules with their sysfs paths
ls /sys/module/

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Troubleshooting

| Issue | Solution | |-------|----------| | modprobe: FATAL: Module not found | Module name may differ — check modinfo or search: find /lib/modules/$(uname -r) -name "name" | | Module loads but device doesn't work | Check dmesg for firmware errors; verify firmware package is installed | | rmmod: ERROR: Module is in use | Check the "Used by" column in lsmod; unload dependent modules first, or use modprobe -r | | Module loads but wrong driver is used | Blacklist the competing module in /etc/modprobe.d/ | | Changes to /etc/modprobe.d/ not taking effect | Unload and reload the module; or reboot; if it's an initramfs module, run sudo dracut --force | | Missing firmware after OS update | Run sudo pacman -S linux-firmware or the specific vendor firmware package | | Module not loading at boot despite /etc/modules-load.d/ entry | Check systemctl status systemd-modules-load; verify the module name is correct with modinfo |

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