Re: How to write kernel modules using C++

Jan Willamowius (jan@janhh.shnet.org)
Sat, 29 May 1999 01:44:55 +0200 (MET DST)

I think using C++ in modules is of quite limited use, but in some cases
it makes sense to snippets of existing code.

Since man people seem to be thinking about using C++ in modules, here
is my example, if you really need to do so. Comments welcome.

- Jan

--- cpp_mod.cpp ---

extern "C"
{
#include <linux/types.h>
#include <linux/module.h>
#include <linux/kernel.h>
}

/* can't include <linux/vmalloc.h>, because it in turn includes */
/* <linux/list.h> which uses C++ keywords a variable names */
extern "C" void * vmalloc(unsigned long size);
extern "C" void vfree(void * addr);
// extern "C" int atexit(void (*function)(void));

/* include this explicitely: g++ might optimize instance in module.h away !*/
static char kernel_version[] = UTS_RELEASE;

MODULE_AUTHOR("Jan Willamowius");
MODULE_DESCRIPTION("Demo for C++ usage in modules");
MODULE_PARM(param1, "i");

static int param1 = 0;

void * operator new(size_t amt)
{
void * pReturn = NULL;
pReturn = vmalloc(amt);
printk("NEW: size = %d returns 0x%p\n", amt, pReturn);
return pReturn;
}

void operator delete( void *p )
{
printk("FREE: ptr = 0x%p\n", p);
vfree(p);
}

/*
int atexit(void (*function)(void))
{
printk("ATEXIT\n");
return 0;
};
*/

class Myclass
{
public:
int c;
void printit();

Myclass();
~Myclass();
};

Myclass::Myclass()
{
c = 1;
printk("*******CONSTRUCTOR %d\n", c );
}

Myclass::~Myclass()
{
}

void Myclass::printit()
{
printk("******* PRINTIT %d\n", c );
}

int init_module()
{
// static Myclass mc;
// mc.printit();
Myclass * mc = new Myclass;
mc->printit();
delete mc;
return 0;
}

void cleanup_module()
{
}

-- 
Jan Willamowius, http://www.willamowius.de/
Microsoft has a year 2000 problem. I'm part of it. I'm running Linux.


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