Subject: Re: SIMH runs NetBSD/vax
To: Anders Magnusson <>
From: Lars Brinkhoff <>
List: port-vax
Date: 03/15/2002 14:05:59
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.

Olaf Seibert <> writes:
> One thing SIMH maybe could do is change the meaning of an uncommon
> sort of instruction that's effectively a No OPeration, which could
> be inserted in the busy-wait. SIMH could treat it like a WAIT
> instruction.

This sounds like a good idea.  I, for one, would really like to
eliminate the busy-wait.  Would this, or one of the other suggestions,
be acceptable?

Lars Brinkhoff     Linux, GCC, PDP-10,
Brinkhoff Consulting    HTTP programming