If you're able to, would you mind linking to some resources about the case you describe in point three where the kernel need deal with an invalid stack pointer? I'm very curious about the underlying causes.
Also, regarding point two, is the cumulative result of those factors you describe (other NMIs being blocked, lack of kernel control, the unreliable heuristic) that a diagnostic NMI may end up never being run?
Also, regarding point two, is the cumulative result of those factors you describe (other NMIs being blocked, lack of kernel control, the unreliable heuristic) that a diagnostic NMI may end up never being run?