>... then one calls a generic function to put this on the interrupt chain.

Unless someone fiddled with my code, this is how the BSD sparc
interrupt handlers work too.  Due to demands made by the clock
interrupt, you can get either your own pointer back (an opaque
thing) or a pointer to the clock arguments.

>the zshard() routine could use some work

The whole driver needs to be rewritten, mostly from scratch. :-)

However:

>take advantage of the vectoring that the chip gives you

Van Jacobson advised me not to do this.  I forget the exact details
as to why, but I trusted he was right...

Chris