For the community wireless network I work on, I am studying the
feasibility of making the NetBSD boot loader supervise reliable software
updates on rooftop routers. I want for the loader to use the watchdog on
the AMD SC520 (486 clone) to regain control from software version N+1
if it "wedges" so that it can revert to version N.

I am assuming that system version N+1 is experimental, so it might disarm
the watchdog if its registers are not protected.  Would it take more than
a page of code in the i386 boot loader to make it "trap" access to the
watchdog-control registers in the SC520?  Without doing a vast amount of
"processor virtualization" work, I want to protect a small I/O region. Is
it possible?

Dave

-- 
David Young             OJC Technologies
dyoung@ojctech.com      Urbana, IL * (217) 278-3933