Re: get_user/copy_from_user

[Ralph Corderoy <ralph@inputplus.demon.co.uk>]

Hi,

> [The  "third"  argument  is  traditionally char *argp, and will be so
> named for this discussion.]"""
> 
> I got a feeling that ioctl can be used similar to printf (va_list,
> stdarg.h etc) and I can pass as many parameters to the ioctl as
> possible (though I wasn;t sure how to extract those parameters from
> the unsigned long arg in xtcsound_ioctl).
> 
> If there's indeed a way to extract the parameters passed to ioctl
> using the unsigned long arg, please let me know. I guess, that would
> be bit cleaner way to do things.

Unless Linux has changed things you can only pass a third arg to ioctl,
not a 4th, etc.  If many parameters need to be passed then the 3rd arg
is a pointer to a parameter block that both user and kernel agree on,
e.g. a struct in a header file.


Ralph.

-
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/
IRC Channel:   irc.openprojects.net / #kernelnewbies
Web Page:      http://www.kernelnewbies.org/