Re: external gpl kernel module build problem on 2.6.26.8-rt16

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello,

On Thu, Apr 23, 2009 at 06:49:03AM -0400, Mark Hounschell wrote:
> Frank Rowand wrote:
> > Mark Hounschell wrote:
> >> I get the following while trying to build this driver. What does it mean.
> >>
> >>  Building modules, stage 2.
> >>  MODPOST 1 modules
> >> WARNING: "__bad_func_type" [/local/work/markh/pci5565-linux/driver/rfm2g.ko]
> >> undefined!
> >>
> >> Then obviously the module doesn't load for the same reason.
> >>
> >> When I grep the kernel for bad_func_type all I see is
> >>
> >> include/linux/rt_lock.h:192:extern int __bad_func_type(void);
> >> include/linux/pickop.h:8:extern int __bad_func_type(void);
> >> include/linux/pickop.h:16:      else __bad_func_type();
> >>                 \
> >> include/linux/pickop.h:27:      else __ret = __bad_func_type();
> >>
> >> Any help or hints would be appreciated
> >>
> >> Thanks in advance
> >> Mark
> > 
> > #define PICK_FUNCTION(type1, type2, func1, func2, arg0, ...)            \
> > do {                                                                    \
> >         if (PICK_TYPE_EQUAL((arg0), type1))                             \
> >                 func1((type1)(arg0), ##__VA_ARGS__);                    \
> >         else if (PICK_TYPE_EQUAL((arg0), type2))                        \
> >                 func2((type2)(arg0), ##__VA_ARGS__);                    \
> >         else __bad_func_type();                                         \
> > } while (0)
> > 
> > And PICK_FUNCTION_RET() uses the same technique.
> > 
> > Something that invokes PICK_FUNCTION() or PICK_FUNCTION_RET() is passing
> > in an arg0 that is not type1 and is not type2.
> > 
> > One easy way to figure out what is invoking PICK_FUNCTION()/PICK_FUNCTION_RET()
> > is to look at the output from the cpp of your driver.  The method I usually
> > use is to add the flags "-C -E" to my compile command (and remove "-c").
> > Then search the cpp output for __bad_func_type.
> > 
> 
> Thanks for the pointer. How might one do this using the kernel build system
> though? Isn't the compile command used actually the kernels compile command?
> Can I assume this would entail modifying the kernels top Makefile in some way?
You can compile using

	make V=1

With that you can see the complete commands.  Then just take the last
command (i.e. the failing one) and do s/-c/-C -E/.

BTW, my guess is that it has to do with spinlocks and you do something
like:

	spinlock_t lock;

	....

	spin_lock_irqsave(lock, flags);

instead of

	spin_lock_irqsave(&lock, flags);

Best regards
Uwe

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
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