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I think we just have a different interpretation > of ABI, or rather are talking about different pieces of ABI. > > I am still asking for never-break serialization format compatibility, i.e. the > more literal save/restore ABI. I'm not asking for full backwards/forwards > compatibility across all kernels version, i.e. the higher level "kernel" ABI. > > To phrase things differently: I am a-ok if kernels are inherently incompatible > because they fundamentally operate differently and/or support different features. > I am not ok if we end up with incompatible kernels because the save/restore > interfaces and payloads are poorly designed, lack abstraction, etc. I can more agree with this, it is mostly what I thought we'd end up doing anyhow with version numbers and growing the structs not replacing them. So you still end up with a version label (string I guess?) because we can break it from time to time, just the version should have the feature mechanism layered under it? I'm fine with that Jason