Re: [PATCH] docs/about: Automatically deprecate versioned machine types older than 6 years

On 30/04/2024 11.55, Daniel P. Berrangé wrote: > On Tue, Apr 30, 2024 at 08:45:29AM +0200, Thomas Huth wrote: > > Old machine types often have bugs or work-arounds that affect our > > possibilities to move forward with the QEMU code base (see for example > > https://gitlab.com/qemu-project/qemu/-/issues/2213 for a bug that likely > > cannot be fixed without breaking live migration with old machine types, > > or https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg04516.html or > > commit ea985d235b86). So instead of going through the process of manually > > deprecating old machine types again and again, let's rather add an entry > > that can stay, which declares that machine types older than 6 years are > > considered as deprecated automatically. Six years should be sufficient to > > support the release cycles of most Linux distributions. > > Reading this again, I think we're mixing two concepts here. > > With this 6 year cut off, we're declaring the actual *removal* date, > not the deprecation date. > > A deprecation is something that happens prior to removal normally, > to give people a warning of /future/ removal, as a suggestion > that they stop using it. > > If we never set the 'deprecation_reason' on a machine type, then > unless someone reads this doc, they'll never realize they are on > a deprecated machine. > > When it comes to machine types, I see deprecation as a way to tell > people they should not deploy a /new/ VM on a machine type, only > use it for back compat (incoming migration / restore from saved > image) with existing deployed VMs. > > If we delete a machine on the 6 year anniversary, then users > don't want to be deploying /new/ VMs using that on the > 5 year anniversary as it only gives a 1 year upgrade window. > > So how long far back do we consider it reasonable for a user > to deploy a /new/ VM on an old machine type ? 1 year, 2 years, > 3 years ? > > > How about picking the half way point ? 3 years ? > > ie, set deprecation_reason for any machine that is 3 years > old, but declare that our deprecation cycle lasts for > 3 years, instead of the normal 1 year, when applied to > machine types. > > This would give a strong hint that users should get off the > old machine type, several years before its finally deleted. Sounds like a good idea, too! Since I have to drop this patch here anyway, could you maybe write such a new patch? (or do you want me to try to formulate this?)