From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53051) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJ2Zc-0003wE-5f for qemu-devel@nongnu.org; Wed, 04 Feb 2015 11:13:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YJ2ZX-00072Y-Vu for qemu-devel@nongnu.org; Wed, 04 Feb 2015 11:13:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45592) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YJ2ZX-00072O-Mm for qemu-devel@nongnu.org; Wed, 04 Feb 2015 11:12:59 -0500 Date: Wed, 4 Feb 2015 16:12:52 +0000 From: "Daniel P. Berrange" Message-ID: <20150204161252.GB3032@redhat.com> References: <20150203190921.GR3354@HEDWIG.INI.CMU.EDU> <20150203201112.6410.67335@loki> <20150203213858.GU3354@HEDWIG.INI.CMU.EDU> <20150204093132.GJ3032@redhat.com> <20150204152013.GW3354@HEDWIG.INI.CMU.EDU> <20150204152432.GZ3032@redhat.com> <20150204155917.GA16281@HEDWIG.INI.CMU.EDU> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20150204155917.GA16281@HEDWIG.INI.CMU.EDU> Subject: Re: [Qemu-devel] RFC: Proposal to add QEMU "Guest Environment Variables" Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Gabriel L. Somlo" Cc: Michael Roth , qemu-devel@nongnu.org On Wed, Feb 04, 2015 at 10:59:18AM -0500, Gabriel L. Somlo wrote: > On Wed, Feb 04, 2015 at 03:24:32PM +0000, Daniel P. Berrange wrote: > > Yes, there is some overhead in setting up QEMU on the host to provide > > the data cloud-init needs, but it isn't all that difficult. For example > > Rich Jones describes how to setup a virtual disk for cloud-init > > > > https://rwmj.wordpress.com/2013/12/10/creating-a-cloud-init-config-disk-for-non-cloud-boots/ > > > > Given the prevalence of cloud-init across distros, I think you'll be hard > > pressed to get them to support an alternative method, even if it is a bit > > simpler at the QEMU setup level. > > Have a look at this: > > http://www.vmware.com/pdf/Scripting_API_23.pdf > > (page 36, GuestInfo Variables). > > It's a rather generic, flexible feature. Some people use it for > early boot, but that's just one of the many use cases, so maybe > focusing on "how to implement early boot configuration" is going > a bit off on a tangent :) > > I'd like to add that mechanism (or at least the host->guest bits) > to qemu, for "feature parity". That should be a good thing, making > it easier to port "whatever" to qemu, without having to massively > rearchitect it to work around a missing feature... > > Also, it's really non-intrusive. At this point, I could implement it > by passing environment strings in via "-smbios file=./Type11EnvStrBlob", > and read them on the guest side via 'dmidecode -t11', with some grep > and awk magic thrown in for good measure :) Perhaps cloud-init project would be interested in using the custom smbios field as a data source for its needs. It already has the concept of pluggable data sources, so adding another could be interesting. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|