Trying to keep this commit distinct from the one where @julien_xen.org moved several pieces of the file back to sys/x86... Still using those names even though this represents a distinct rework of some of the pieces. There are a fair number of trivial wrappers around headers present, I prefer symbolic links since git does support those.

I've got a preliminary version of the CTASSERT in place, appeared at to function for the purpose you were thinking of. I note xen_intr.c already makes the assumption in many places. Notably nearly every function which takes a struct intsrc *base_isrc as an argument implicitly assumes the struct intsrc * can be converted to a struct xenisrc *. I agree this is a Good Idea to add them.

You're really that interested in having the removal of 2 lines be a distinct commit? I only noticed the situation when I looked at the diff then noticed xai_activehi and xai_edgetrigger no longer occurred anywhere. Until that point those were in struct xen_arch_isrc.

I believe the CTASSERTS() added in D30909 should fulfill your desire for those. I agree they do make rather a bit of sense.

Now notable D32876 shows how isrc->xi_cookie can move to isrc->xi_arch.xai_cookie. Just an issue of getting that decision made.