From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: Xen 4.1 + Linux compiled with PVH == BOOM Date: Mon, 23 Dec 2013 20:56:50 -0500 Message-ID: <20131224015650.GA2191@pegasus.dumpdata.com> References: <20131220175735.GA619@phenom.dumpdata.com> <1387624194.1025.70.camel@dagon.hellion.org.uk> <52B8046302000078000A9C8C@nat28.tlf.novell.com> <52B8235D02000078000A9CB1@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <52B8235D02000078000A9CB1@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel@lists.xensource.com, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On Mon, Dec 23, 2013 at 11:49:49AM +0000, Jan Beulich wrote: > >>> "Jan Beulich" 12/23/13 10:39 AM >>> > >>>> Ian Campbell 12/21/13 12:10 PM >>> > >>On Fri, 2013-12-20 at 12:57 -0500, Konrad Rzeszutek Wilk wrote: > >>> But perhaps that is not the way to do it and we should just cherry-pick > >>> 30832c06a8d1f9caff0987654ef9e24d59469d9a in Xen 4.1? > >> > >>I think we should do both, i.e. backport 30832c06a8d1 now to solve the > >>immediate problem and then look at fixing unstable to be more accepting > >>of new features which it doesn't yet know about. > > > >Hmm, not sure - without a split between necessary to be understood > >and acceptable to be unknown ones, I'm not sure either model will be > >the right thing. > > And actually, in the case at hand the "BOOM" is correct: If the kernel tells > the hypervisor that it needs a feature the hypervisor doesn't even recognize, > it's surely wrong to ignore this. The mistake here is for the kernel to require But it does not ignore it. It checks later on in construct_dom0 whether the 'required' parameters are present, like: if ( test_bit(XENFEAT_supervisor_mode_kernel, parms.f_required) ) > that feature statically in the first place - that should be done only if the kernel > could _only_ boot in PVH mode. The feature is not marked as "required" but rather - it can utilize said extension (so supported). I am advocating that the calleer checks that all of the required pieces are correct - and it can ignore the ones it has no idea off (which it does for some of the Xen ELF notes - ignores them if it has no idea of what they are). > > Jan >