unexpected bahavior with module - relocation problem ?
Matthias Fuchs
matthias.fuchs at esd-electronics.com
Wed May 8 18:56:47 EST 2002
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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