Right now in virt-manager we only track a VM's OS name (win10, fedora28, etc.) during the VM install phase. This piece of data is important post-install though: if the user adds a new disk to the VM later, we want to be able to ask libosinfo about what devices the installed OS supports, so we can set optimal defaults, like enabling virtio. There isn't any standard libvirt XML field to track this kind of info though, so apps have to invent their own schema. nova and rhev do it indirectly AFAICT. gnome-boxes does it directly with XML like this: <metadata> <boxes:gnome-boxes xmlns:boxes="https://wiki.gnome.org/Apps/Boxes"> <os-id>http://fedoraproject.org/fedora/28</os-id> .... </boxes:gnome-boxes> </metadata> I want to add something similar to virt-manager but it seems a shame to invent our own private schema for something that most non-trivial virt apps will want to know about. I was thinking a schema we could document with libosinfo, something like <metadata> <libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... <os-id>http://fedoraproject.org/fedora/28</os-id> </libosinfo> </metadata>

On Wed, Sep 05, 2018 at 09:28:52AM +0100, Daniel P. Berrangé wrote: > On Tue, Sep 04, 2018 at 03:44:12PM -0400, Cole Robinson wrote: > > Right now in virt-manager we only track a VM's OS name (win10, fedora28, > > etc.) during the VM install phase. This piece of data is important > > post-install though: if the user adds a new disk to the VM later, we want to > > be able to ask libosinfo about what devices the installed OS supports, so we > > can set optimal defaults, like enabling virtio. > > > > There isn't any standard libvirt XML field to track this kind of info > > though, so apps have to invent their own schema. nova and rhev do it > > indirectly AFAICT. gnome-boxes does it directly with XML like this: > > > > <metadata> > > <boxes:gnome-boxes xmlns:boxes="https://wiki.gnome.org/Apps/Boxes"> > > <os-id>http://fedoraproject.org/fedora/28</os-id> > > .... > > </boxes:gnome-boxes> > > </metadata> > > > > I want to add something similar to virt-manager but it seems a shame to > > invent our own private schema for something that most non-trivial virt apps > > will want to know about. I was thinking a schema we could document with > > libosinfo, something like > > > > <metadata> > > <libosinfo > > xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... > > <os-id>http://fedoraproject.org/fedora/28</os-id> > > </libosinfo> > > </metadata> > > Yes, I would like to see this standardized under <matadata>. > Me too and what Cole suggested looks fine.

On Wed, Sep 05, 2018 at 03:37:22PM +0100, Daniel P. Berrangé wrote: > On Wed, Sep 05, 2018 at 02:01:42PM +0200, Martin Kletzander wrote: >> On Wed, Sep 05, 2018 at 09:28:52AM +0100, Daniel P. Berrangé wrote: >> > On Tue, Sep 04, 2018 at 03:44:12PM -0400, Cole Robinson wrote: >> > > Right now in virt-manager we only track a VM's OS name (win10, >> fedora28, >> > > etc.) during the VM install phase. This piece of data is important >> > > post-install though: if the user adds a new disk to the VM later, >> we want to >> > > be able to ask libosinfo about what devices the installed OS >> supports, so we >> > > can set optimal defaults, like enabling virtio. >> > > >> > > There isn't any standard libvirt XML field to track this kind of >> info >> > > though, so apps have to invent their own schema. nova and rhev do it >> > > indirectly AFAICT. gnome-boxes does it directly with XML like this: >> > > >> > >   <metadata> >> > >     <boxes:gnome-boxes >> xmlns:boxes="https://wiki.gnome.org/Apps/Boxes"> >> > >       <os-id>http://fedoraproject.org/fedora/28</os-id> >> > >       .... >> > >     </boxes:gnome-boxes> >> > >   </metadata> >> > > >> > > I want to add something similar to virt-manager but it seems a >> shame to >> > > invent our own private schema for something that most non-trivial >> virt apps >> > > will want to know about. I was thinking a schema we could >> document with >> > > libosinfo, something like >> > > >> > > <metadata> >> > >   <libosinfo >> > > xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... >> > >     <os-id>http://fedoraproject.org/fedora/28</os-id> >> > >   </libosinfo> >> > > </metadata> >> > >> > Yes, I would like to see this standardized under <matadata>. >> > >> >> Me too and what Cole suggested looks fine. > > It occurs to me that we actually need more than just the os-id value. > > When you query devices for a given OS, you'll often be told that multiple > devices are compatible, and the mgmt app can decide which of them to then > use. > > So if we want consistency when later hotplugging, we should make a record > of which devices we decided to use too, so if the mgmt app changes its > preference, we still know what we originally picked. > > eg to express that we use virtio-net and virtio-blk (even if virtio-scsi > was supported by the OS): > >   <metadata> >     <libosinfo > xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... >       <os id="http://fedoraproject.org/fedora/28"/> >       <device id="http://pcisig.com/pci/1af4/1000"/> >       <device id="http://pcisig.com/pci/1af4/1001"/> >     </libosinfo> >   </metadata> > > Note, I'm suggesting using an 'id' attribute, rather than naming the > element 'os-id', to be more closely aligned with osinfo schema. > I'm not against that <device id =''/> but it is going to take some effort to properly specify what is really meant by that.  The fact that some device model was chosen for a particular device does not necessarily mean that it is requested as the default.  It only means what is actually encoded in the XML already, that is a particular model for a particular device.

On Thu, Sep 06, 2018 at 10:04:35AM -0400, Cole Robinson wrote: > On 09/06/2018 09:04 AM, Martin Kletzander wrote: > > On Wed, Sep 05, 2018 at 03:37:22PM +0100, Daniel P. Berrangé wrote: > > > On Wed, Sep 05, 2018 at 02:01:42PM +0200, Martin Kletzander wrote: > > > > On Wed, Sep 05, 2018 at 09:28:52AM +0100, Daniel P. Berrangé wrote: > > > > > On Tue, Sep 04, 2018 at 03:44:12PM -0400, Cole Robinson wrote: > > > > > > Right now in virt-manager we only track a VM's OS name (win10, > > > > fedora28, > > > > > > etc.) during the VM install phase. This piece of data is important > > > > > > post-install though: if the user adds a new disk to the VM later, > > > > we want to > > > > > > be able to ask libosinfo about what devices the installed OS > > > > supports, so we > > > > > > can set optimal defaults, like enabling virtio. > > > > > > > > > > > > There isn't any standard libvirt XML field to track this kind of > > > > info > > > > > > though, so apps have to invent their own schema. nova and rhev do it > > > > > > indirectly AFAICT. gnome-boxes does it directly with XML like this: > > > > > > > > > > > >   <metadata> > > > > > >     <boxes:gnome-boxes > > > > xmlns:boxes="https://wiki.gnome.org/Apps/Boxes"> > > > > > >       <os-id>http://fedoraproject.org/fedora/28</os-id> > > > > > >       .... > > > > > >     </boxes:gnome-boxes> > > > > > >   </metadata> > > > > > > > > > > > > I want to add something similar to virt-manager but it seems a > > > > shame to > > > > > > invent our own private schema for something that most non-trivial > > > > virt apps > > > > > > will want to know about. I was thinking a schema we could > > > > document with > > > > > > libosinfo, something like > > > > > > > > > > > > <metadata> > > > > > >   <libosinfo > > > > > > xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... > > > > > >     <os-id>http://fedoraproject.org/fedora/28</os-id> > > > > > >   </libosinfo> > > > > > > </metadata> > > > > > > > > > > Yes, I would like to see this standardized under <matadata>. > > > > > > > > > > > > > Me too and what Cole suggested looks fine. > > > > > > It occurs to me that we actually need more than just the os-id value. > > > > > > When you query devices for a given OS, you'll often be told that multiple > > > devices are compatible, and the mgmt app can decide which of them to then > > > use. > > > > > > So if we want consistency when later hotplugging, we should make a record > > > of which devices we decided to use too, so if the mgmt app changes its > > > preference, we still know what we originally picked. > > > > > > eg to express that we use virtio-net and virtio-blk (even if virtio-scsi > > > was supported by the OS): > > > > > >   <metadata> > > >     <libosinfo > > > xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"... > > >       <os id="http://fedoraproject.org/fedora/28"/> > > >       <device id="http://pcisig.com/pci/1af4/1000"/> > > >       <device id="http://pcisig.com/pci/1af4/1001"/> > > >     </libosinfo> > > >   </metadata> > > > > > > Note, I'm suggesting using an 'id' attribute, rather than naming the > > > element 'os-id', to be more closely aligned with osinfo schema. > > > > > > > I'm not against that <device id =''/> but it is going to take some > > effort to > > properly specify what is really meant by that.  The fact that some > > device model > > was chosen for a particular device does not necessarily mean that it is > > requested as the default.  It only means what is actually encoded in the > > XML > > already, that is a particular model for a particular device. > > > > Yeah I'm a bit confused by this as well, it's not exactly clear to me > how we would use or set XML like that for virt-manager, and how other > apps would be expected to consume it. > That's what I though of when trying to say we need to define the meaning of that. What might be meaningful is if the user selects a particular *default* model for new devices (e.g. disks should be IDE by default) then that option could be honoured when adding a new device of that type (unless requested otherwise). I'm not sure if that's what Daniel meant by that.