From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: xen_emul_unplug on xen 4.1, HVM guest 2.6.38 Date: Wed, 26 Oct 2011 09:49:42 -0400 Message-ID: <20111026134942.GB31609@phenom.dumpdata.com> References: <0050AA2F452257584F0AAA0B@nimrod.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <0050AA2F452257584F0AAA0B@nimrod.local> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Alex Bligh Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Wed, Oct 26, 2011 at 02:17:25PM +0100, Alex Bligh wrote: > I am running Xen 4 and want users to be able to install arbitrary HVM > images. We want both PV and emulated drivers to appear. The reason > for this is for compatibility with images that were prepared for > Xen 3.3, which assume emulated devices exist at boot time (particularly > for running the boot loader). > > If I do not specify on the boot line xen_emul_unplug=never, then > under some guest OS's (e.g. Ubuntu Natty (2.6.38)), the domU kernel > unplugs the non-PV devices, which is undesirable in my application. > > I cannot arbitrarily change the kernel command line because it is > in effect set by the user's image. > > Therefore what I need to do is prevent Xen4 offering the facility > to unplug the devices in the first place. Setting "(unpluggable 0)" > in the config for the emulated NICs and disks does not appear > to prevent them getting unplugged; what may be happening is that > domU tries to unplug them (but fails) but still doesn't use them. > Is there a way to signal from dom0 that the kernel really shouldn't > unplug this stuff. xen_pci_platform=0 in your guest config should do it.