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I'm assuming you've read http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise/ http://www.freedesktop.org/wiki/Software/systemd/InterfaceS

by jononor 11y ago

I'm assuming you've read http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise/ http://www.freedesktop.org/wiki/Software/systemd/InterfaceSt... and http://www.freedesktop.org/wiki/Software/systemd/InterfacePortabilityAndStabilityChart http://www.freedesktop.org/wiki/Software/systemd/InterfacePo... Which APIs do you refer to that are not documented as an stable interface, but should be?

lmm 11y ago
The internal ones, as I said. E.g. you can't write a drop-in replacement for logd, or even a reader of its files. IIRC systemd doesn't support non-kdbus dbus - or indeed older kernels at all.
- jononor 11y ago
  Here is documentation for the on-disk journal format (with links to the JSON+export format): http://www.freedesktop.org/wiki/Software/systemd/journal-files http://www.freedesktop.org/wiki/Software/systemd/journal-fil... systemd supports non-kdbus DBus, that is essentially what every deployed systemd system is using. Including this laptop, which is on latest systemd (227) with upstream kernel (4.2.5, kdbus not included). Why is it important to be able to replace journald (assuming that is what you meant by logd)?
  - lmm 11y ago
    Being able to replace individual pieces is the heart of open source - the only reason the GNU project was able to get off the ground is because it could swap out individual parts of unix without having to write the whole thing from the ground up. More generally, forking only works if you can do it on a granular level. So if I have an idea for improving journald and for whatever reason the official maintainers won't accept my patches, I should be able to release my own fork of just journald and if people like it then it will become more popular and maybe be mainlined or maybe not. If I have to fork the whole of systemd to do that then it's too much overhead.
    - jononor 11y ago
      journald is a separate module in the systemd tree, so this is very likely possible. You have both the code implementing the daemon and the one using it available to study, so the interface.
      - lmm 11y ago
        The issue is that systemd might change that interface at any time, even in a minor or patch release. Because systemd's released as a single monolithic project, they don't have to commit to any standardization, deprecation cycle or the like for the interface between components.
        jononor 11y ago
        Yep, no stable interface for journald. Someone is gonna have to prove to them it is needed, by implementing something useful that utilizes said interface. but as documented previously in thread, for plenty of their components they have committed to stable, documented interfaces.
- jononor 11y ago
  systemd supports 'older kernels', just not old ones. systemd 227, released last month, requires Linux 3.7+. That version was release December 2012, or nearly 3 years ago.

by jononor 11y ago

lmm 11y ago

The internal ones, as I said. E.g. you can't write a drop-in replacement for logd, or even a reader of its files. IIRC systemd doesn't support non-kdbus dbus - or indeed older kernels at all.

jononor 11y ago
Here is documentation for the on-disk journal format (with links to the JSON+export format): http://www.freedesktop.org/wiki/Software/systemd/journal-files http://www.freedesktop.org/wiki/Software/systemd/journal-fil... systemd supports non-kdbus DBus, that is essentially what every deployed systemd system is using. Including this laptop, which is on latest systemd (227) with upstream kernel (4.2.5, kdbus not included). Why is it important to be able to replace journald (assuming that is what you meant by logd)?
- lmm 11y ago
  Being able to replace individual pieces is the heart of open source - the only reason the GNU project was able to get off the ground is because it could swap out individual parts of unix without having to write the whole thing from the ground up. More generally, forking only works if you can do it on a granular level. So if I have an idea for improving journald and for whatever reason the official maintainers won't accept my patches, I should be able to release my own fork of just journald and if people like it then it will become more popular and maybe be mainlined or maybe not. If I have to fork the whole of systemd to do that then it's too much overhead.
  - jononor 11y ago
    journald is a separate module in the systemd tree, so this is very likely possible. You have both the code implementing the daemon and the one using it available to study, so the interface.
    - lmm 11y ago
      The issue is that systemd might change that interface at any time, even in a minor or patch release. Because systemd's released as a single monolithic project, they don't have to commit to any standardization, deprecation cycle or the like for the interface between components.
      - jononor 11y ago
        Yep, no stable interface for journald. Someone is gonna have to prove to them it is needed, by implementing something useful that utilizes said interface. but as documented previously in thread, for plenty of their components they have committed to stable, documented interfaces.
jononor 11y ago
systemd supports 'older kernels', just not old ones. systemd 227, released last month, requires Linux 3.7+. That version was release December 2012, or nearly 3 years ago.