Where to put the include file which defines ioctl numbers?

AustinMarton · 08-01-2011, 08:31 PM

Hello,

I have come across this a few times and wonder if I am doing things correctly. Say I write a new char driver (drivers/char/mychar.c) which defines some ioctls in it's header file:

Code:

#define MYCHAR_IOC_MAGIC  0xE4 /* magic number */
#define MYCHAR_IOC_MODE_GET	_IOR(MYCHAR_IOC_MAGIC, 0, int)
#define MYCHAR_IOC_MODE_SET	_IOW(MYCHAR_IOC_MAGIC, 1, int)
#define MYCHAR_IOC_MAXNR 2

Now I want to use these definitions in my user space application, so I place the header file at linux/include/linux/mychar.h and include it (because linux/include is already added as an include dir to my user space applications make file).

The problem is, what if I have some structures or definitions in the .h file that won't compile in user space? And what about the linux/include directory getting flooded with unorganised driver header files?

My other options I guess would be to duplicate the definitions in a user space header file, or perhaps have two header files for the driver (one that only contains the ioctls for user space).

Any opinions appreciated.

Regards,
Austin.

bastl · 08-03-2011, 03:00 PM

Your char device is your interface between userspace appls. and module/hardware.
Your haeder file describes your interface standards (IOCTLs) for both the user space appl. and your module !
So the haeder file have to be the same included in any appl./module wants to use this interface and must only include interface definitions.

I can not folow, why it should not be possible to compile this haeder file in user space ? (for help you should post some code)
In haeders there is nothing that makes any byte of programm code so there is no execution limitation and so no compilation limitation.

The right place for your haeder file should be "/usr/include/linux/yourhaeder.h" or if you can specify a category (maybe usb) of your device "/usr/include/linux/usb/yourhaeder.h"
You should then submit your driver as a patch:
http://linuxtv.org/wiki/index.php/De...submit_patches

So you can #include <linux/usb/yourhaeder.h>

Else you can place it to "/usr/include/ modulename /yourhaeder.h" if it is only you using this module.

So you can #include < modulename /yourhaeder.h>

AustinMarton · 08-04-2011, 04:30 PM

Cheers for your response. That convention makes sense. The reason my header file wasn't compiling in user space was that I had defined some structures that used kernel data types, but I have just moved them into the driver itself.

Thanks,
Austin.