Re: compat_ioctl question

[Paul Fulghum <paulkf@microgate.com>]

Arnd Bergmann wrote:
> 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.

I missed that approach, thanks.

> Yes, that would be the right solution. I've started this
> some time ago, but never finished it:
> http://www.uwsg.iu.edu/hypermail/linux/kernel/0511.0/1732.html
>
> > 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.

I'll look at that.

You have given me precisely the information I need.

I just wanted to be sure I did not pursue a dead end
and have people go 'ewwww... why did you do it that way?'

Thanks,
Paul

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