Re: compat_ioctl question
From: Arnd Bergmann
Date: Thu Apr 26 2007 - 18:09:30 EST
On Friday 27 April 2007, Paul Fulghum wrote:
> Arnd Bergmann wrote:
> > It depends a lot on what your specific driver does in the ioctl
> > handler, but normally you should define a compat_ioctl() function.
> > What driver are you talking about?
> All use the same set of ioctl() codes that
> are peculiar to the synclink drivers.
So you are interested in the MGSL_* set of ioctls, right?
AFAICS, they are all compatible, with the exception of
MGSL_IOCGPARAMS and MGSL_IOCSPARAMS.
Fortunately, these two have different ioctl numbers on
64 bit, so you can define a new
#define MGSL_IOCSPARAMS32 _IOR(MGSL_MAGIC_IOC,0,struct _MGSL_PARAMS32)
#define MGSL_IOCGPARAMS32 _IOR(MGSL_MAGIC_IOC,1,struct _MGSL_PARAMS32)
and handle both versions in the ioctl function.
> Defining compat_ioctl() seems to be the best way, but
> that will require modifying the base tty code to allow
> the individual tty drivers to register compat_ioctl().
Yes, that would be the right solution. I've started this
some time ago, but never finished it:
> Currently the tty file ops do not include that and
> tty_io.c does not register a compat_ioctl(), instead
> relying on compat_ioctl.h and compat_ioctl.c
Just adding the hook in tty_io.c should be trivial, please do that.
If you like, you can also move the vt ioctls in order to reduce
the size of fs/compat_ioctl.c.
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