Hmm. Well, apparently I've stepped on a few toes by not using the BSDI mutex code verbatim.

My position is this:

* I don't think we can use the BSDI mutex code verbatim because we intend to keep legacy SPL support and it would take as much work addressing that in the BSDI mutex code as it would doing a new core-mutex piece from scratch.

* I think we CAN use the *WITNESS* code pretty much verbatim. The reason it isn't in patch set #1 is because the witness code is not going to be useful until we start unwinding the SPL code in the system, and that is not going to happen until *after* heavy weight interrupt threads are implemented. Until that time (maybe a month or two from now?) it's just extra baggage. It's the next logical step to take after the heavy weight interrupt code is made to work, not before.

The witness code isn't going to help us for just the Sched and Giant mutexes... simple KASSERT's deal with those situations.

In regards to the general project. If people want to try to port the BSDI mutex code directly then be my guest. I've got a patch set that works now ... I can successfully make buildworld on an SP machine with it. You can try porting the BSDI mutex code with or without the patchset I've already got, but if after a month or two if you still don't have something that works I would recommend going back to the piecemeal approach I have taken, starting with my patchset.

I won't be angry or anything if people decide to take this course, even though I think it's the wrong course to take. But you guys have to decide what to do ASAP.