Kernel Issues

This page collects kernel module loading and runtime troubleshooting notes.

vermagic Mismatch

Typical error pattern:

disagrees about version of symbol
invalid module format

Check:

modinfo ./mydriver.ko | grep vermagic
uname -r

The module must be built against headers that match the running kernel.

Related page:

• Kernel Version and vermagic

Module Loads but Device Node Is Missing

Check:

dmesg | tail -50
ls /dev
ls /sys/class

Possible causes:

• device_create() was not called.
• class_create() failed.
• The probe function was never called.
• The Device Tree compatible string does not match the driver.

Related pages:

• Character Device Basics
• Platform Driver and Device Tree Binding

Interrupt Does Not Fire

Check:

cat /proc/interrupts
sudo dmesg -w

Possible causes:

• Wrong GPIO pin.
• Wrong interrupt parent.
• Wrong IRQ trigger type.
• Pinmux or pull configuration is incorrect.
• The hardware signal is not toggling.