[RFC PATCH 0/3] liveupdate: Move to feature flags for LUO and memfd ABI compatibility

[Sean Christopherson]

On Thu, Sep 10, 2026, Jason Gunthorpe wrote:
> Sean's initial email was asking for strict never-break ABI compatability
> rules on top, and that is what I've been reacting to.

No, I was never asking for that.  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.