ubuntu18.04 vscode kernel module program ERROR: identifier "KBUILD_MODNAME" is undefine - linux

Question

My environment: Ubuntu 18.04, kernel: linux-5.3.0-53 vscode: lastest
Command for fixing linux/module.h not find asm/xxx.h
cd /usr/src/linux-headers-5.3.0-53/include
sudo ln -s asm-generic/ asm
My c_cpp_properties.json
{
"configurations": [
{
"name": "Linux",
"includePath": [
"${workspaceFolder}/**",
"/usr/include",
"/usr/local/include",
"/usr/src/linux-headers-5.3.0-53/include",
"/usr/src/linux-headers-5.3.0-53-generic/include",
"/usr/src/linux-headers-5.3.0-53/arch/x86/include",
"/usr/src/linux-headers-5.3.0-53/include/uapi",
"/usr/lib/gcc/x86_64-linux-gnu/7.5.0/include"
],
"defines": [
"__GNUC__",
"__KERNEL__"
],
"compilerPath": "/usr/bin/gcc",
"cStandard": "gnu11",
"cppStandard": "gnu++14",
"intelliSenseMode": "clang-x64"
}
],
"version": 4
}
My hello_module.c, a simple Linux kernel module program.
//a simple linux kernel module program.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
MODULE_LICENSE("GPL"); //error here
static int hello_init(void){
printk(KERN_ALERT "hello world\n");
return 0;
}
static void hello_exit(void){
printk(KERN_ALERT "goodbye world\n");
}
module_init(hello_init);
module_exit(hello_exit);
then ERROR：
identifier "KBUILD_MODNAME" is undefined
How to fix? Please help me..

Answer 1

KBUILD_MODNAME is automatically defined by the Makefile when you build your kernel module, so you will not find it anywhere in the kernel header files.
To stop vscode from complaining about undefined KBUILD_MODNAME identifier, just add a dummy definition to your c_cpp_properties.json file in the "defines" section
"defines": [
"KBUILD_MODNAME=\"hello_module\"",
"__GNUC__",
"__KERNEL__"
],
That should make vscode happy =)
The value you define for KBUILD_MODNAME does not really matter, since it is automatically defined during the make process.
I have not understood if this is your only problem, or if you also have problems to compile the module. If yes let me know and we will figure out how to solve that too!