Subject: Re: map user memory in kernel
To: Chuck Silvers <>
From: Jaromir Dolecek <>
List: tech-kern
Date: 11/06/2005 23:52:48
On Sun, Nov 06, 2005 at 01:52:16PM -0800, Chuck Silvers wrote:
> On Sun, Nov 06, 2005 at 09:49:31PM +0100, Jaromir Dolecek wrote:
> > > the logical page can be paged out and replaced with a different
> > > physical page when it's paged backed in, so we cannot use the
> > > vm_page pointer for this purpose.
> > 
> > Could we use vm_map_entry ?
> how?  could you be more specific?

I mean, use address of appropriate vm_map_entry as the futex wait
channel base. However, that is process-specific too, sorry for the
noise :)

Okay, back to anon:

> > vm_anon is per-process thing, so we don't want to use that -
> > we need to use the vm_page or vm_object.

> also, I believe there are already cases where will we replace the anon
> that is used to represent a given page of process anonymous memory
> with a different anon, and I plan on adding more.  we should not rely
> on the anon remaining the same.

If the anonymous memory is shared, both processes actually use the same anon
structure, right? Why would you want to replace the anon with
different one?

Jaromir Dolecek <>  
-=- 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.          -=-