On Sun, Feb 11, 2007 at 02:27:22PM -0500, Arnaud Lacombe wrote:
quoted text
> I'd like to change the size of the `vnd_size' member of struct vnd_ioctl
> from `int' to `u_quad_t' (or any other unsigned 64bits type, but
> u_quad_t is used by `struct vattr->va_size').

uint64_t should be preferred for new code.

quoted text
> Currently, it is quite easy make it either negative or greater than
> 2^32[1]. This field is only used when we call vnconfig(8) with -v
> (verbose).
>=20
> Does the change needs any compatibility layer to be added ?=20

The process is quite simple:  keep a copy of the current structure with
a different name (e.g., oldvnd_ioctl), and create new ioctl commands
referencing that structure with the name OXXX.

E.g.:

#define OVNDIOCSET       _IOWR('F', 0, struct oldvnd_ioctl)

Then you add an entry in ioctl handler for those commands that do what
they're supposed to do (i.e., in that case convert the value), and put
those specific parts under COMPAT_40.

--=20
Quentin Garnier - cube@cubidou.net - cube@NetBSD.org
"You could have made it, spitting out benchmarks
Owe it to yourself not to fail"
Amplifico, Spitting Out Benchmarks, Hometakes Vol. 2, 2005.