[openstack-dev] [oslo] Any reason why not have 'choices' parameter for ListOpt()?
doug at doughellmann.com
Mon Mar 26 20:27:47 UTC 2018
Excerpts from melanie witt's message of 2018-03-26 12:28:02 -0700:
> On Mon, 26 Mar 2018 14:12:52 -0500, Matt Riedemann wrote:
> > On 3/26/2018 6:24 AM, ChangBo Guo wrote:
> >> What's your use case for ListOpt, just make sure the value(a list) is
> >> part of 'choices' ? Maybe we need another parameter to distinguish
> > It came up because of this change in nova:
> > https://review.openstack.org/#/c/534384/
> > We want to backport that as a bug fix which is a mitigation for
> > performance degradation issues with QEMU patches for Spectre and Meltdown.
> > However, in the backport we wanted to restrict the ListOpt to a single
> > value, "pcid". The idea is to restrict the new option to a single value
> > in stable branches.
> > Then in master, we could remove the 'choices' kwarg so operators can
> > define their list as they wish.
> > If we were do implement this generically in ListOpt, I suppose 'choices'
> > would mean that the specified list must be a subset of the defined
> > choices list. So in the backport patch, we'd just have choices=[None,
> > 'pcid'] and you can either specify None or 'pcied' for that option
> > (default to None).
> > Right now the code that's relying on this option just has a hard-coded
> > check for the value which is OK.
> I'm not sure if this helps, but we do already have some example of a
> ListOpt with 'choices' for the VNC auth_schemes:
> Could we do something similar for the backport of the CPU flags patch?
Oh, look, another feature that's already in the library. :-)
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