Subject: Re: Upgrade of `struct vnd_ioctl'
To: Martin Husemann <>
From: David Laight <>
List: tech-kern
Date: 02/11/2007 21:58:40
On Sun, Feb 11, 2007 at 08:33:16PM +0100, Martin Husemann wrote:
> On Sun, Feb 11, 2007 at 02:27:22PM -0500, Arnaud Lacombe wrote:
> > Does the change needs any compatibility layer to be added ? 
> Yes - the size of ioctl arguments is encoded in the ioctl cmd code, so you
> need to rename the old struct and allocate new numbers for all vnd ioctls
> (with the same symbolic name as before), then provide the old (now renamed)
> ioctls under the appropriate COMPAT define.

Because the size is encoded into the command code, you don't need new
numbers - just different names.


David Laight: