On Mon 23 Aug 1999, Leo Weppelman wrote:
> going to look like, so the userland transition on the ioctl-interface has
> only to be done once. To support other disklabel formats, the best thing
> todo seems to reserve a certain amount of slack in the structure and use
> unions in the definition. So label formats can be squeezed in.

Forget this, it's a bad idea! A better approach might be to pass a pointer,
and size (and maybe a label-type) through the ioctl. This info is of constant
size while supporting a large variety of disklabels. The kernel subsystem
handling the ioctl can decide on the type if the label is supported (thus
passing the type in the ioctl is mostly a performace enhancement). 

Leo.