Re: UVM and the NULL page

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Mon, Aug 01, 2016 at 04:46:34PM +0000, Eduardo Horvath wrote:
> On Mon, 1 Aug 2016, Joerg Sonnenberger wrote:
> 
> > I disagree. While it is nice to assert this property in the pmap, it is
> > the wrong place. First of all, all pmaps need to be audited, at least on
> > platforms with shared address space. It's not specific to x86. Second,
> > part of the problem is that UVM does not handle its own constraints
> > correctly. That means it is possible that some of the (then failing)
> > requests could be fulfilled by correct code. In short, handling it in
> > the pmap doesn't actually solve the problem completely either.
> 
> I don't understand.  If you can't enter the mapping into the TLB, who 
> cares what UVM does?

If UVM tries [0, n] and could have picked [1, n+1] as page numbers as
well, will it try the latter after the pmap insert failed for the
former?

Joerg