Re: mmap implementation advice needed.

[Johnny Billquist <bqt%softjar.se@localhost>]

On 2018-03-31 14:43, Mouse wrote:
> (Should this be moved to somewhere VAX-specific, maybe?)

Yes...

> > The problem was/is (if I understood it right), that someone can mmap
> > more than 1G, and that will never be possible to map on the VAX.
>
> Well...close.
>
> > The P0 space is only 1G, and the same is true for the P1 space.  But
> > P0 and P1 is disjunct, so don't try to think of them as contiguous
> > space.
>
> But they are contiguous: the top of P0 space abuts the bottom of P1
> space.

Yes, but as you noted below, they grow from the opposite ends, meaning 
you really then need the full tables for both spaces for them to 
connect. Which I (and I guess in the end you) find unlikely to be desirable.

> > So, anything trying to grab more than 1G will never be possible.
>
> Probably.  Theoretically possible, but unlikely to ever be implemented.

Right.

> > But it would appear that the MI part don't give any hooks to stop a
> > process from going just that.
>
> Isn't the VAX pmap code in a position to reject attempts to allocate
> virtual space it doesn't support?

I think that was the problem Ragge faced, but it also seems there 
actually was a way, based on answers that came in.

  Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
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