Re: NetBSD in SIMH vax with 512 MB RAM

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> I'd say the rightest thing to do is compute - either mechanically or
>> by hand - what amount of physical memory would put SLR as close as
>> possible to 200000 without going over, then cap physical memory size
>> at that value (preferably with a message).
> Yep, but that is not possible, since ~everything is possible to
> change dynamically and we cannot expand the SPT on-demand since it is
> located in physical memory.

I guess I didn't pick a good wording.  I wasn't talking about anything
that would mean fiddling the SPT at runtime.  I was talking about
something like

/* With more than 497M of physical memory, SLR exceeds 20000. */
#define MAXPHYSMEM (497 << 20)

(or whatever the actual value is), and then, at some appropriate point,

	if (avail_end > MAXPHYSMEM) avail_end = MAXPHYSMEM;

To get fancy, instead of a #define, do a little run-time arithmetic,
possibly involving the kernel size and maybe other things (attached
buses, perhaps?).

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