On Wednesday, 2021-01-20 at 10:59:24 +01, Igor Mammedov wrote: > On Tue, 19 Jan 2021 11:30:52 -0500 > Eduardo Habkost <ehabk...@redhat.com> wrote: > >> On Tue, Jan 19, 2021 at 04:27:56PM +0000, David Edmondson wrote: >> > On Tuesday, 2021-01-19 at 10:20:56 -05, Eduardo Habkost wrote: >> > >> > > Hi, >> > > >> > > Thanks for the patch. Getting rid of special -feature/+feature >> > > behavior was in our TODO list for a long time. >> > > >> > > On Tue, Jan 19, 2021 at 02:22:06PM +0000, David Edmondson wrote: >> > >> "Minus" features are applied after "plus" features, so ensure that a >> > >> later "plus" feature causes an earlier "minus" feature to be removed. >> > >> >> > >> This has no effect on the existing "-feature,feature=on" backward >> > >> compatibility code (which warns and turns the feature off). >> > > >> > > If we are changing behavior, why not change behavior of >> > > "-feature,feature=on" at the same time? This would allow us to >> > > get rid of plus_features/minus_features completely and just make >> > > +feature/-feature synonyms to feature=on/feature=off. >> > >> > Okay, I'll do that. >> > >> > Given that there have been warnings associated with >> > "-feature,feature=on" for a while, changing that behaviour seems >> > acceptable. >> > >> > Would the same be true for changing "-feature,+feature"? (i.e. what this >> > patch does) Really: can this just be changed, or does there have to be >> > some period where the behaviour stays the same with a warning? >> >> I actually expected warnings to be triggered when using >> "-feature,+feature" as well. If we were not generating warnings >> for that case, it will need more careful evaluation, just to be >> sure it's safe. Igor, do you remember the details here? > As part of preparation to define/create machines via QMP, > I plan to post patch(s) to deprecate +-features in 6.0 > (including special casing for -feat behavior (affects x86/sparc only)) > and drop support for +-feat in 2 releases. > So we should end up with canonical property behavior only like all other > CPUs and devices.
In that case I will abandon this change and focus on getting my upstack consumer to switch away from using +-. Thanks. dme. -- Sometimes these eyes, forget the face they're peering from.