[Simh] vax idle for NetBSD

[Paul Koning]

> On Dec 11, 2018, at 1:40 PM, Mark Pizzolato <Mark at infocomm.com> wrote:
> 
> The simple test with the VAX simulator is to enable any OS form of idling and 
> boot the simulator.  While sitting at the ROM >>> prompt idle kicks in precisely 
> as expected.  Similarly, when booting VMS, idling also occurs as expected.

I see it now on NetBSD, takes about 20 seconds from the time the OS goes idle (the login prompt).

Interesting that the boot prompt would idle, since that's not NetBSD...

Tried it on ELX8, I see roughly the same.  Tried "show -d idle" and it reports something plausible sounding:

idle enabled, stability wait = 20s, minimum sleep resolution = 1ms

I then continued, and noticed that the simulation goes CPU bound for 30 seconds, then returns to idling.  Tried it again, same result.  Is that caused by the clock catching up?  Come to think of it, clock catchup is not all that useful for this system, is there a way to have the timekeeping be real simulation time only, so time at the SIMH prompt does not count?  The clock is used for scheduling etc. but not for timekeeping (not in any OS I have seen for that machine, anyway).

	paul