This is insufficient for Alpha and other 64 bit architectures. I think what you are asking for is really a 'void *'.

The other issue here is that your idea of an opaque API/ABI indicator is in conflict, unless you say that this is a pointer, and then format the initial information pointed to by the pointer. Otherwise, you will need a small indirection structure that's pointed to the pointer, AND which contains the API/ABI identifier (i.e. you will need two, not one piece of information for that -- which is what you show, but not what you describe in your text).

This is moderately bogus.

Specifically, if you are going to register in new types without an assigned numbers authority (e.g. if I have a vendor private extension, which I wish to implement, yet not have collide with someone else's vendor private extension or a future FreeBSD "standard extension"), then you need to implement a registration interface for named registration, and use *that*.

The easiest way to do this would be to ensure that you use the *runtime* kernel address as your identifier, which guarantees that it will be unique in any given system.

I think it has to. The reason he has this is pretty clear from his crypto work, and the reason for the linked list is to, in the limit, allow a linear traversal of the list elements to find data that's relevent to you.

It's kind of ugly, but "anything that works is better than anything that doesn't"... it at least guarantees that it *can* work.