I have written a simple char module. Sometimes it loads and sometimes not. 2 problems are present and do not always show up.

Problem 1:
My register_chrdev(MY_MAJOR, "My Mod", &fsOps), with MY_MAJOR=120, works just fine. However if I reboot and try to load the module, I can't register 120. If I change MY_MAJOR=150 and recompile, works fine. Until I reboot.

Problem 2:
MY_ADDRESS = 0x3f8
MY_RANGE = 8

create_region(MY_ADDRESS, MY_RANGE, "MY_MOD") fails although check_region succeeds.

Error Msg: Device is busy.

This is frustrating.

Rick

I think you HAVE to make yourself more clear


Hano

try different possiblities,

1) Try with major no between 241 to 255 for testing purposes
for ore detail about device nos see,

documentation/devices.txt (orsomething similar) on source code path

2) check /proc/iomem (i exactly don't remember name as i am sitting on window machine) serch for something similar (in /proc)if not fonund to check wether the region is allocated.

1)MN's in the ranges 60 to 63, 120 to 127, and 240 to 254 are reserved for local and experimental use. No real (serious) driver would be assigned such numbers).

2)Dynamic allocation:
If the major number specified, is set to 0 (register_chrdev), then the function selects a free number and returns it.

If you didn't find a suitable answer to your question, you might want to try http://kernelnewbies.org/

--Kervin