Resolving "Exec format error" When Loading Kernel Modules

Resolving "Exec format error" When Loading Kernel Modules

Overview

An "Exec format error" during modprobe indicates a mismatch between the running kernel and the module's build configuration. Typically, the module's vermagic (version magic) string does not match the output of uname -r. The following procedure outlines how to verify and correct this issue.

Steps to Resolve

1. Verify Kernel Version vs. Module Vermagic
   a. Check your running kernel:

   uname -r
   

   b. Inspect the module's vermagic:

   modinfo /lib/modules/$(uname -r)/updates/dvb-core/dvb-core.ko | grep vermagic
   

   c. Ensure the vermagic string exactly matches uname -r (including SMP, compiler version, and other flags).

2. Install Matching Kernel Headers

   sudo apt update
   sudo apt install linux-headers-$(uname -r)
   

   This provides the build directory at /lib/modules/$(uname -r)/build.

3. Remove Stale Modules
   If older-version modules remain, delete them so depmod won’t load the wrong binaries:

   sudo rm /lib/modules/$(uname -r)/updates/dvb-core/dvb-core.ko
   sudo rm /lib/modules/$(uname -r)/updates/frontends/cxd2099.ko
   sudo rm /lib/modules/$(uname -r)/updates/frontends/ddbridge.ko
   sudo depmod -a
   

   (Adjust paths as needed.)

4. Rebuild and Install the Module(s)
   Build drivers manually:

   cd /path/to/ddbridge-source
   make clean
   make
   sudo make install
   

   Or using the build script:
   Build Script Section

5. Update Module Dependencies

   sudo depmod -a
   

6. Load the Module

   sudo modprobe ddbridge -vvv
   

   Successful insertion confirms that vermagic now matches and the module is compatible.

Verification

After loading, verify with:

dmesg | tail -n 20
lsmod | grep ddbridge

Ensure no "Exec format error" appears and that ddbridge is listed as loaded.

Document prepared to assist with consistent resolution of kernel module version mismatches.