Difference between sun4, sun4c and sun4m subarchitectures

I don't suppose it occurred to either of you to actually go and check? NetBSD's code is available for inspection, and while I haven't checked, I feel certain OpenBSD's is too. I just had a quick look at the NetBSD code. The biggest differences seem to be in the pmap, which deals with the MMU; there are other checks for SUN4 vs SUN4M vs SUN4C scattered around, but they are mostly various drivers that know things like "this device appears attached to obio only on 4c machines". It's possible to build a kernel supporting any desired subset of the three types; if you build a kernel supporting more than one type, you will pay a marginal speed penalty since some things will make run-time checks for the architecture, checks which are effectively done at compile time in a single-architecture kernel. You might want to check it before suggesting it. I just had a look and found nothing of any real use to an OS writer. It talks only in generalities far too vague to write code to. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B