Subject: Re: remplacing page mappings behind uvm
To: YAMAMOTO Takashi <>
From: Manuel Bouyer <>
List: tech-kern
Date: 11/30/2007 12:55:46
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, and to maintain
changes in qemu-dm too (or other hardware emulators when they show up in

Manuel Bouyer, LIP6, Universite Paris VI. 
     NetBSD: 26 ans d'experience feront toujours la difference