Subject: Re: SIMH runs NetBSD/vax
To: Anders Magnusson <>
From: Tom Ivar Helbekkmo <>
List: port-vax
Date: 03/11/2002 10:58:02
Anders Magnusson <> writes:

>> I noticed that the kernel is busy-waiting when idle. Can this not be
>> improved? I am used to the Motorola 68000 which has a WAIT instruction
>> that halts the CPU until an interrupt occurs...
> Unfortunately no, the vax do not have any such instruction, busy-wait
> is the only solution.

Maybe it would be a good idea to pretend that one exists?  Add a
fictive VAX model that differs from the one that SIMH actually
emulates only in that it has a special WAIT instruction, and then have
the kernel use that when it detects that it's running on SIMH.  It
might be necessary to make SIMH do something that allows the kernel to
realize that's what it's on, of course...

Puritanism -- the haunting fear that someone, somewhere, may be happy.