Messages in this thread | | | From | "Khimenko Victor" <> | Date | Sat, 20 Feb 1999 20:08:30 +0300 (MSK) | Subject | Re: First steps in module hacking... |
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In <36CEDDA6.9630D713@phya1.physik.uni-bielefeld.de> Thorsten Westheider (twesthei@phya1.physik.uni-bielefeld.de) wrote: > Hi,
> I'm very interested in a little bit kernel hacking, so I bought > myself the book 'Linux device drivers' (O'Reilly) and started > to code a simple 'Hello world' module
> Part 1: > ------- > #define __NO_VERSION__
> #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/version.h>
> char kernel_version[] = UTS_RELEASE;
> int init_module(void) > { > printk("<1>Here we are :-)\n"); > return 0; > }
> Part 2: > ------- > #define __NO_VERSION__
> #include <linux/kernel.h> > #include <linux/module.h>
> void cleanup_module(void) > { > printk("<1>Now we're gone :-("); > }
> Compiling works just fine,
> root@weyoun:/home/twesthei/C/kernel > make > gcc -D__KERNEL__ -I/usr/src/linux/include -O2 -Wall -Wstrict-prototypes > -fomit-frame-pointer -pipe -fno-strength-reduce -m486 -malign-loops=2 > -malign-jumps=2 -malign-functions=2 -DCPU=586 -DMODULE -DEXPORT_SYMTAB > -c skull_init.c -o skull_init.o > gcc -D__KERNEL__ -I/usr/src/linux/include -O2 -Wall -Wstrict-prototypes > -fomit-frame-pointer -pipe -fno-strength-reduce -m486 -malign-loops=2 > -malign-jumps=2 -malign-functions=2 -DCPU=586 -DMODULE -DEXPORT_SYMTAB > -c skull_clean.c -o skull_clean.o > ld -r skull_init.o skull_clean.o -o skull.o
> but I can't insmod that piece of code because of
> root@weyoun:/home/twesthei/C/kernel > insmod skull > ./skull.o: unresolved symbol printk
> What??? Any help appreciated ;-)
You have kernel with MODVERSIONS support but module is compiled without MODVERSIONS support. No-go.
Add -DMODVERSIONS -include /usr/src/linux/include/linux/modversions.h to gcc command line and remove __NO_VERSION__ from .c files ...
BTW why printk("<1>Here we are :-)\n");, not printk(KERN_ALERT "Here we are :-)\n"); ?
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