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] disable qemu PCI devices in HVM domains

To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, "Ian Jackson" <Ian.Jackson@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] disable qemu PCI devices in HVM domains
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Sat, 13 Dec 2008 21:05:49 +1100
Cc: Steven Smith <steven.smith@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
Delivery-date: Sat, 13 Dec 2008 02:06:19 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <C569370F.20329%keir.fraser@xxxxxxxxxxxxx>
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: <AEC6C66638C05B468B556EA548C1A77D0154FF9F@trantor> <C569370F.20329%keir.fraser@xxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Aclbuhoqr0BLOGEhQ/CaC00xxoX3kABS0/IwAADgswAAAAsTIA==
Thread-topic: [Xen-devel] disable qemu PCI devices in HVM domains
> > Is the 'pci unplug' as simple as making a call somewhere like
> > pci_unplug(id of ide adapter)? I'm concerned that Windows may not
> > this.
> My own opinion is that the ioports are fine, but they should be
> from
> the xen-platform-pci device's ioport bar. Also we ought to document
> ports in xen-platform-pci's source file, as it's going to start
> messy in there.
> I'm not sure if the approach taken by the Citrix drivers could be at
> useful. Cc'ing Steven Smith in case he has any comments to make.

Citrix use fixed ports for logging. The problem with using
xen-platform-pci's ioport range is that I can only get to them once the
windows pci bus driver has enumerated all the devices, and it's too late
by then as Windows has already enumerated PDO's for all the devices. The
only way around this would be to send an 'unplug' event to xen to remove
the PCI devices, but is the standard PCI bus emulated by qemu hotplug
capable? And would windows even cope with a hotplug event that early in
the boot process?

A completely different way of solving this (as per another previous
email) is for qemu to (optionally) emulate things at the int13 level
rather than at the pci device level. That way there would be no PCI
device at all and Windows would only ever see my drivers. We can already
do this for net, but obviously that isn't required for booting
(normally). So /dev/hd[a-d] would be PCI devices and anything else would
be hooked into int13.

If only Windows were more like Linux...


Xen-devel mailing list