Re: Questions about copy-on-write

[Rian Hunter]

Marcus Brinkmann wrote:

> > i think the general understanding has currently bin that 
> > mapping/unmapping will be a privilegded operation. ie. only hurd servers 
> > should be doing, or most precisely mostly physmem. untrusted tasks won't 
> > really be unmapping/mapping, they will be using containers and closing 
> > containers, and dying. physmem will take care of the actual business of 
> > mapping and copying and etc.
> >    
>
> This is a misunderstanding, or maybe a careless wording.  A mapping
> operation is always from one task to another, and you don't really say
> anything about that, so I don't know if you mean it the right or the
> wrong way.
>  
Yeah, I meant it the right way. I meant that physmem will take care of 
all the low-level details of mapping to and from tasks in L4. A mapping 
operation made by one task to another will be carried out by physmem.

>  
>
> > physmem will be predictably mature into being a very intelligent and 
> > thoughtful program, yet not very complicated as it won't (ideally) 
> > contain any policy on memory.
> >    
>
> This is not true.  Physmem introduces a lot of policy, for example it
> will enforce memory consumption restrictions, and how to share memory.
> It will not contain any policy on managing _virtual_ address space of
> a task.  But it will contain policy about _physical_ memory management
> (hence its name).
>
>  
I meant policy on how a task will manage its memory, I should have been 
more specific again.

scrutiny!
-rian