Issue with ioctl commands - Linux version 2.6.35.7+

Chetan Nanda chetannanda at gmail.com
Tue Dec 27 06:39:18 EST 2011


Hi All,

I am facing a strange issue with the ioctl commands, and not able to find
what wrong I am doing.
I am trying with a dummy kernel driver and implemented ioctl command as
follow:

in my_ioctl.h
#define READHWREG_MAGIC_NUMBER 0x15
#define READHWREG_CAM_READPE _IOR(READHWREG_MAGIC_NUMBER, 1, int*)

But the value of 'READHWREG_CAM_READPE' is comes out to be different in
userspace (in the application) and kernel space (in the driver).

In userspace I used ioctl as
...
   printf("\ncommand %x \n",READHWREG_CAM_READPE); <-- command 80041501
   error = ioctl(g_DevFileId, READHWREG_CAM_READPE);
..

In kernel space

int readHwReg_ioctl(struct inode *node, struct file *filp, unsigned int
cmd,  unsigned long arg)
{
...
   printk("\n%d %s cmd = %x\n",__LINE__,__FUNCTION__,cmd); <--- cmd =
bee6a9d4
...
}


I am not able to figure out the root cause,
Please help to check...

Thanks,
Chetan Nanda
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