Building kernel modules on BBB rev c with Debian

[ec1...@gmail.com]

Hi,

I have a newer BBB with Debian and am trying to build a hello world kernel module.  Does anyone have the recipe for that?  I also have an older BBB with 2GB Angstrom.  To build the hello world module on that one, do this:

Create a directory and save a "Makefile" with this text.  Note: indentations must be tabs and not spaces:

obj-m += hello.o

all:
          make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
          make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Now make a file called "hello.c":

/* Source file .c */
/*  hello.c */

#include <linux/module.h>   // Needed by all modules
#include <linux/kernel.h>   // Needed for KERN_ALERT
#include <linux/init.h>     // Needed for the macros


static int hello_init(void)
{
   printk(KERN_ALERT "Hello, My module!\n");
   return 0;
}


static void hello_exit(void)
{
   printk(KERN_ALERT "Goodbye, My module!\n");
}

save both files.  Run "make"

Won't compile?  It's because the sock distro doesn't have the kernel headers and development environment installed and set up.  Here's what you have to do.  This will take about 45 minutes:

opkg update
opkg upgrade

opkg install kernel-headers
opkg install kernel-dev


reboot the BBB

cd  /usr/src/kernel
make scripts
ln -s /usr/src/kernel /lib/modules/`uname -r`/build

re-run:

opkg upgrade        // completes silently

run make in the folder with your hello.c and Makefile.

It should build in about 1/2 second and the last line output will be something like "leaving kernel..."

now run:

ldmod hello.ko

dmesg // you should see the Hello text from the printk()

rmmod hello.ko

dmesg // you should see the Goodbye text from printk()

[dumb looks free]

Hello,

this worked for me on Debian
http://dumb-looks-free.blogspot.fr/2014/06/beaglebone-black-bbb-kernal-headers.html

good luck

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