This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] [RFC Patch] Support for making an E820 PCI hole in tools

To: Keir Fraser <keir@xxxxxxx>
Subject: Re: [Xen-devel] [RFC Patch] Support for making an E820 PCI hole in toolstack (xl + xm)
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Mon, 15 Nov 2010 13:15:44 -0500
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, bruce.edge@xxxxxxxxx, gianni.tedesco@xxxxxxxxxx, stefano.stabellini@xxxxxxxxxxxxx
Delivery-date: Mon, 15 Nov 2010 10:18:18 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C9072307.A021%keir@xxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20101115170302.GA7414@xxxxxxxxxxxx> <C9072307.A021%keir@xxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.20 (2009-06-14)
> >  1). Did not work for me - I am not sure why but I had the hardest time do
> >      hypervisor_populate_physmap - it would just hang the guest.
> For a PV guest you don't need to do any alloc/free/move memory hypercalls.
> You rewrite your own p2m to relocate mfns where you want them in pfn space.
> Then some hypercalls just to update the m2p array to match.

Ok, I can play with that see what fun/havoc I can create.
> >  2). It is much simple to parse the E820 in the Linux kernel than actually
> >      creating new E820 entries in the kernel (hypercall), making a bunch of
> >      hypervisor calls that unmap, then remap the space, filling out the P2M
> >      with INVALID_MFN, and doing all of that before the "real" Linux kernel
> >      actually starts (all would have to be done in xen_start_kernel).
> >      I have a sinking feeling tha the upstream community would not like it
> >      this that much.
> Well it is all quite Xen specific, so I'm surprised.

Oh, there was another reason that I so obvious that I completly forgot. DomU
has no idea where the host PCI hole starts. In most cases it is at 3GB (or even
further up - 3.5GB), but a quick look for 'Allocating PCI resources starting 
at Google shows that there are some that start at 1.2G.

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>