Hello, I’m unsure where to post this, but posting it here as it’s MANJARO kernels related. If this doesn’t belong here, I’m happy to move it. Would appreciate any pointers for where to post this
Issue
Put it short, I want to give a go at creating a hello kernel module & loading it up.
I have 6.7.7-1-MANJARO kernel, whose latest headers have a different name and version to them 6.7.0-3-rt6-MANJARO.
When I build the hello module & try loading it, I get Invalid module format error, which seems to be cause by version mismatch. More details below:
More Info
Finding headers folder
The /usr/lib/modules/6.7.7-1-MANJARO module has neither the include, nor build under it.
Looking up the package manager:
$ pacman -Qs linux67
local/linux67 6.7.7-1
The Linux67 kernel and modules
local/linux67-rt-headers 6.7_rt6-3
Header files and scripts for building modules for Linux67-rt kernel
Shows the headers for my current kernel version are installed. Looking up the directories of kernel headers gives:
$ pacman -Ql linux67-rt-headers
... etc.
linux67-rt-headers /usr/lib/modules/6.7.0-3-rt6-MANJARO/build/vmlinux
linux67-rt-headers /usr/src/linux67-rt
Check for newer headers version
So my kernel headers version is 6.7.0-3-rt6-MANJARO.
I’ve synced up & upgradde pacman with pacman -Syu (all is up-to-date) and looked up the latest header version:
$ pacman -Ss kernel | grep -iA1 headers
...etc.
core/linux67-rt-headers 6.7_rt6-3 [installed]
Header files and scripts for building modules for Linux67-rt kernel
---
...etc.
Appears, I have the latest version.
Finding where to point Makefile
So looking up usr lib modules gives:
$ ls /usr/lib/modules/
6.7.0-3-rt6-MANJARO 6.7.7-1-MANJARO
Under the 6.7.0-3-rt6-MANJARO directory there’s only 1 directory called build. So clearly that’s where I need to point my hello module Makefile to:
KERNELDIR ?= /usr/lib/modules/6.7.0-3-rt6-MANJARO/build
Loading module
When I build the my hello module and get my hello.ko, loading it gives error:
$ sudo insmod hello.ko
insmod: ERROR: could not insert module hello.ko: Invalid module format
Looking up more detail gives the following error:
$ sudo dmesg | tail
[ 2788.287361] hello: version magic '6.7.0-3-rt6-MANJARO SMP preempt mod_unload ' should be '6.7.7-1-MANJARO SMP preempt mod_unload '
Question:
What is exactly the problem here? These seem to be the correct headers & checking pacman shows there’s newer better to install to match the kernel version.
Extra Info:
project Makefile:
LDDINC=$(PWD)/../include
EXTRA_CFLAGS += -I$(LDDINC)
ifeq ($(KERNELRELEASE),)
# Assume the source tree is where the running kernel was built
# You should set KERNELDIR in the environment if it's elsewhere
KERNELDIR ?= /usr/lib/modules/6.7.0-3-rt6-MANJARO/build
# The current directory is passed to sub-makes as argument
PWD := $(shell pwd)
modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions *.mod modules.order *.symvers
.PHONY: modules modules_install clean
else
# called from kernel build system: just declare what our modules are
obj-m := hello.o
endif
hello.c module
#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("DUAL BSD/GPL");
static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, cruel world!\n");
}
module_init(hello_init);
module_exit(hello_exit);
vs_code json for imports
{
"configurations": [
{
"name": "driver",
"defines": [
"__KERNEL__",
"MODULE"
],
"compilerPath": "/usr/bin/gcc",
// "compilerPath": "/usr/bin/clang",
"cStandard": "c11",
"cppStandard": "c++14",
"intelliSenseMode": "gcc-x64",
// "intelliSenseMode": "linux-clang-x64",
"configurationProvider": "ms-vscode.makefile-tools",
"includePath": [
"${workspaceFolder}/**",
"/usr/lib/modules/6.7.0-3-rt6-MANJARO/**",
"/usr/lib/modules/6.7.7-1-MANJARO/**",
"/usr/src/linux67-rt/**",
"/usr/lib/gcc/x86_64-pc-linux-gnu/14.1.1/include"
],
"compilerArgs": [
"-nostdinc",
"-include", "/usr/src/linux67-rt/include/linux/kconfig.h",
"-include", "/usr/src/linux67-rt/include/linux/compiler_types.h"
]
}
],
"version": 4
}
There’s probably a bunch of stuff here that doesn’t need to be, but I have no idea what’s needed yet, so I included it all until the squiggly line was gone.