Subject: Re: remplacing page mappings behind uvm
To: YAMAMOTO Takashi <email@example.com>
From: Manuel Bouyer <firstname.lastname@example.org>
Date: 11/30/2007 13:17:45
On Fri, Nov 30, 2007 at 09:08:39PM +0900, YAMAMOTO Takashi wrote:
> > On Fri, Nov 30, 2007 at 12:31:06PM +0900, YAMAMOTO Takashi wrote:
> > > > Although it'a gross hack, it works for Xeni386. It also works on Xenamd64,
> > > > up to process exit: it triggers an assersion in pmap_destroy() because
> > > > pmap_remove() is not called on the hacked memory ranges.
> > >
> > > how about tweaking device pager instead of maintaining these hacks?
> > I did look at this when I implemented these ioctls. It's not so easy.
> > mmap() on devices will use offsets, but the physical pages are not contigous,
> > yet xen wants them mapped as a contigous VM area. It can be done but would
> > mean a driver more complex than the simple ioctl I have now,
> isn't an array enough to convert offset -> machine address?
No, because machine addresses are not contigous, but xen wants a contigous
virtual adresses. Also, you have to pass a domain id in some way
> i'm not sure if it's a good idea to make vm deal with it
> in order to simplify this very uncommon driver.
pmap_enter_ma() is also used in other places.
> > and to maintain
> > changes in qemu-dm too (or other hardware emulators when they show up in
> > Xen).
> does qemu-dm work without modifications currently?
There are some minor changes, mostly to deal with pkgsrc, and our
/dev/tap. This part is not touched.
Manuel Bouyer, LIP6, Universite Paris VI. Manuel.Bouyer@lip6.fr
NetBSD: 26 ans d'experience feront toujours la difference