unexpected bahavior with module - relocation problem ?

unexpected bahavior with module - relocation problem ?

[Matthias Fuchs]

Hi all,

I got a little problem that I cannot really understand.
I wrote a little device driver for a 405 PPC board. The driver registers a miscdevice.

Normally all misc devices are listed under /proc/misc.
My first attempt resulted in a /proc/misc looking like this:

# cat /proc/misc
187          <- "test" is missing here !
185 gpio

The code is attached. When I change the init stuff for the miscdevice structure
a little bit (see below with WORKING defined), I got the expected bahavior.

Is this a relocation problem when loading the module ? In the two version the NAME string
sits in different segments. Is there a way to fix the problem by a compiler switch ? Is this a PPC issue ?
I noticed that the Linux rtc driver uses the same code as I do, but it does not have the problem.
The difference is that my code is a lkm and mot compiled into the kernel.

Matthias

...

#define NAME   "test"
#define MINOR  187

#ifdef WORKING
static char name[]=NAME;
#endif

static struct file_operations my_fops =
{
...
};

static struct miscdevice my_miscdev =
{
#ifdef WORKING
   name:  name, // results in correct bahavior
#else
   name:  NAME, // results in missing module name in /proc/misc
#endif
   minor: MINOR,
   fops:  &my_fops
};

int __init my_init(void)
{
   misc_register(&my_miscdev);
   return 0;
}


void __exit my_exit(void)
{
   misc_deregister(&my_miscdev);
}

module_init(my_init);
module_exit(my_exit);


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Re: unexpected bahavior with module - relocation problem ?

[Matthias Fuchs]

Hi,

I found the problem. It seems to be a problem with the insmod tool in the busybox
that I am using on my target (0.61pre from cvs).

Matthias


Matthias Fuchs wrote:

>
> Hi all,
>
> I got a little problem that I cannot really understand.
> I wrote a little device driver for a 405 PPC board. The driver registers
> a miscdevice.
>
> Normally all misc devices are listed under /proc/misc.
> My first attempt resulted in a /proc/misc looking like this:
>
> # cat /proc/misc
> 187          <- "test" is missing here !
> 185 gpio
>
> The code is attached. When I change the init stuff for the miscdevice
> structure
> a little bit (see below with WORKING defined), I got the expected bahavior.
>
> Is this a relocation problem when loading the module ? In the two
> version the NAME string
> sits in different segments. Is there a way to fix the problem by a
> compiler switch ? Is this a PPC issue ?
> I noticed that the Linux rtc driver uses the same code as I do, but it
> does not have the problem.
> The difference is that my code is a lkm and mot compiled into the kernel.
>
> Matthias
>
> ...
>
> #define NAME   "test"
> #define MINOR  187
>
> #ifdef WORKING
> static char name[]=NAME;
> #endif
>
> static struct file_operations my_fops =
> {
> ...
> };
>
> static struct miscdevice my_miscdev =
> {
> #ifdef WORKING
>   name:  name, // results in correct bahavior
> #else
>   name:  NAME, // results in missing module name in /proc/misc
> #endif
>   minor: MINOR,
>   fops:  &my_fops
> };
>
> int __init my_init(void)
> {
>   misc_register(&my_miscdev);
>   return 0;
> }
>
>
> void __exit my_exit(void)
> {
>   misc_deregister(&my_miscdev);
> }
>
> module_init(my_init);
> module_exit(my_exit);
>
>
>
>


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