Unsupported systemd-confext and sysext on bootc

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Hi!

I was surprised to see this
docs: Document that systemd-confext and sysext are unsupported by mohan-shash · Pull Request #2436 · bootc-dev/bootc · GitHub

(documented in Filesystem - bootc)

…as I had gotten the impression that this was the direction forward or at least a fully valid path that worked well with the bootc “model”. I have heard bootc-people recommended exploring sysext in the bootc matrix chat for example, and seen things like Extending Fedora Atomic Desktops using systemd system extensions :: All Systems Go! 2025 :: pretalx. So I don’t understand if this is something new or something that never worked.

I am left in a confused state

  • is it “only” not recommended currently as it MAY not work as intended? If I were to pick a non-complex example from https://fedora-sysexts.github.io/ together with bootc fedora 44 base image, is it expected to work or not? Is the base-case not working or just special cases?
  • the 2 layer limit (FILESYSTEM_MAX_STACK_DEPTH) make it sound like it is a more fundamental issue - will it ever be resolved or are sysexts/confexts simply not a good fit for bootc going forward?

  • The /etc case in particular is expected to become tractable: configuring the composefs backend with etc = none

    • what does setting etc = none mean?

Would be grateful for anyone knowledgeable to inform me - and please talk to me as the consumer / end-user I am (not a developer with knowledge about the bootc internals).