[openstack-dev] [nova] How to handle hw_pointer_model image meta?

Matt Riedemann mriedem at linux.vnet.ibm.com
Thu Oct 13 19:18:23 UTC 2016


On 10/13/2016 12:30 PM, Matt Riedemann wrote:
> In Newton we replaced the CONF.libvirt.use_usb_tablet option with
> CONF.pointer_model, both default to creating a usb tablet input device
> for HVM guests in the libvirt driver.
>
> To straddle backward compatibility with use_usb_tablet=False, we added
> None and ps2mouse as options for the pointer_model config option, which
> basically mean if you specify those you get whatever default input
> device there is (ps2mouse for libvirt x86).
>
> The hw_pointer_model image metadata takes precedence over the config
> option in nova.
>
> I noticed today that the hw_pointer_model ImageMeta object property is
> using a field with a single enum, 'usbtablet'. So while the config
> option lets you set None/ps2mouse/usbtablet, the image meta value can
> only be usbtablet if it's set.
>
> This is important because we don't have hw_pointer_model defined in the
> glance libvirt image metadefs:
>
> https://github.com/openstack/glance/blob/13.0.0/etc/metadefs/compute-libvirt-image.json
>
>
> I'd like to add it but the only value you can have for it is 'usbtablet'
> right now. Having a single enum value seems kind of weird, but maybe
> that's fine. I only found 3 other image metadefs in glance that had
> 'None' as possible enum values.
>
> So would we define 'ps2mouse' as a hw_pointer_model option in nova or
> just add hw_pointer_model to glance and it has a single enum value for
> setting it, which is usbtablet? If you don't want usbtablet then you
> don't add hw_pointer_model to your image - HOWEVER - given we default
> CONF.pointer_model='usbtablet' we're still going to try and set it when
> creating the guest, which may or may not fail depending on your other
> config for that compute host (e.g. any non-kvm/qemu virt_type will fail).
>
> Alternatively we could change the default value of CONF.pointer_model to
> be None and then it's purely an opt-in behavior, but it would be a
> change in default behavior for guests on kvm/qemu hosts.
>

FWIW this is what the proposed metadef change looks like:

https://review.openstack.org/#/c/386137/

-- 

Thanks,

Matt Riedemann




More information about the OpenStack-dev mailing list