DKMS - Dynamic Kernel Module Support

Overview

DKMS automatically rebuilds kernel modules when new kernels are installed. It maintains module source code and compiles against each kernel version.

DKMS Configuration

Create /usr/src/<module>-<version>/dkms.conf:

PACKAGE_NAME="mymodule"
PACKAGE_VERSION="1.0"
BUILT_MODULE_NAME[0]="mymodule"
DEST_MODULE_LOCATION[0]="/updates"
AUTOINSTALL="yes"
REMAKE_INITRD="no"

# For multiple modules
BUILT_MODULE_NAME[1]="mymodule_helper"
DEST_MODULE_LOCATION[1]="/updates"

Directory Structure

/usr/src/mymodule-1.0/
├── dkms.conf
├── Makefile
├── mymodule.c
└── mymodule.h

DKMS Commands

# Add module to DKMS tree
dkms add -m mymodule -v 1.0
# or from source directory
dkms add /usr/src/mymodule-1.0

# Build module
dkms build -m mymodule -v 1.0

# Install module
dkms install -m mymodule -v 1.0

# Build and install in one step
dkms install -m mymodule -v 1.0

# Remove module
dkms remove -m mymodule -v 1.0 --all

# Check status
dkms status

Advanced Configuration

# dkms.conf with build options
PACKAGE_NAME="mymodule"
PACKAGE_VERSION="1.0"
CLEAN="make clean"
MAKE[0]="make -C ${kernel_source_dir} M=${dkms_tree}/${PACKAGE_NAME}/${PACKAGE_VERSION}/build"
BUILT_MODULE_NAME[0]="mymodule"
BUILT_MODULE_LOCATION[0]="build/"
DEST_MODULE_LOCATION[0]="/updates/dkms"
AUTOINSTALL="yes"

# Kernel version restrictions
BUILD_EXCLUSIVE_KERNEL="^4\."
BUILD_EXCLUSIVE_ARCH="x86_64"

Creating DKMS Packages

# Create tarball for distribution
dkms mktarball -m mymodule -v 1.0

# Create Debian package
dkms mkdeb -m mymodule -v 1.0

# Create RPM package
dkms mkrpm -m mymodule -v 1.0

Troubleshooting

# View build log
cat /var/lib/dkms/mymodule/1.0/build/make.log

# Force rebuild
dkms remove -m mymodule -v 1.0 -k $(uname -r)
dkms install -m mymodule -v 1.0 -k $(uname -r)

# Build for specific kernel
dkms build -m mymodule -v 1.0 -k 5.15.0-generic

Common Use Cases

• NVIDIA/AMD proprietary drivers
• VirtualBox guest additions
• Wireless drivers (broadcom-wl, rtl8821ce)
• Third-party filesystem modules (ZFS, NTFS3G)