Subject: Re: map user memory in kernel
To: None <tech-kern@netbsd.org>
From: Jaromir Dolecek <jdolecek@NetBSD.org>
List: tech-kern
Date: 11/05/2005 17:57:31
On Sat, Nov 05, 2005 at 05:03:19PM +0100, Joerg Sonnenberger wrote:
> On Sat, Nov 05, 2005 at 03:32:00PM +0000, Emmanuel Dreyfus wrote:
> > On Sat, Nov 05, 2005 at 12:22:45PM +0100, Wolfgang Solfrank wrote:
> > > So no need to actually map the page into memory.  Just make a more or
> > > less unique address out of the address given (like e.g. use the physical
> > > address on machines where physical and virtual address sizes match) and be
> > > done with it.
> > 
> > But what if the page where the address is gets paged out? I can't 
> > rely on a physical address in that situation.
> 
> What about explicitly wiring the page and using the normal ulimits to
> decide when this breaks?

We don't want to wire the page - we don't want to provide random user
processes a way to wire down the page.

Jaromir
-- 
Jaromir Dolecek <jdolecek@NetBSD.org>            http://www.NetBSD.cz/
-=- We can walk our road together if our goals are all the same;     -=-
-=- We can run alone and free if we pursue a different aim.          -=-