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But you said specifically "...and systemd has broken userspace a lot." What did you mean by this? It seems like a complete nonsense statement in the context of

But you said specifically "...and systemd has broken userspace a lot." What did you mean by this? It seems like a complete nonsense statement in the context of user space breakage of the form the kernel is responsible for. The main clash between the kernel maintainers and the systemd maintainers was over systemd reading the kernel argv in an error prone way to trigger debug information. Other than that the interactions seem completely minimal. Linus Torvalds uses systemd at work and at home.

SwellJoe 9y ago
"What did you mean by this? It seems like a complete nonsense statement in the context of user space breakage of the form the kernel is responsible for." Does it? systemd is the init, the service manager, the interface to D-bus (and kernel devs had a bit of a tussle with the systemd devs about kdbus), the logging interface of most services (possibly including kernel logs), etc. systemd interacts with both the kernel directly (as the system init, as one interface to cgroups and namespaces, etc.) and with users (as everything else it does). I like it, but I understand the Borg accusations. "The main clash between the kernel maintainers and the systemd maintainers was over systemd reading the kernel argv in an error prone way to trigger debug information." Searching the LKML for systemd seems to indicate otherwise. It seems like there have been a few scuffles over the years. I don't subscribe to the LKML or read it religiously and haven't for many years, so I'm mostly guessing based on context, but the context seems clear to me. Again, I ask, if not systemd, then which init is Linus talking about?
- cthalupa 9y ago
  (Disclaimer: I hate systemd) The issue isn't him not knowing what systemd is, or not knowing that that is the init system Linus is talking about. He is aware of both. His issue is with your claim that systemd has broken userspace. You haven't seemed to provide any evidence of this being the case.
  - SwellJoe 9y ago
    We may simply be using different terminology. systemd has had bugs (a lot of them), many of which impacted the system at a high level (being the init and everything else), sometimes due to ineractions with the kernel, sometimes due to interactions with other parts of the system. Perhaps others wouldn't call that "userspace", I dunno. I figure if it affects users trying to run software it's "userspace". But, I'm happy to take the "broke userspace" assertion back if you don't like the term. Let's just say systemd has had a lot of bugs, sometimes stupid ones, and sometimes stubbornly held on to despite kernel devs or other devs asking for changes. I would hope we're not arguing about whether systemd has had an exciting number of bugs and compatibility issues (I think we can all agree on that, even if we like systemd). I inferred a bunch from my recollection of how the LKML has talked about systemd in the past. I assumed Linus was talking about systemd and that when he says he doesn't trust it, it was about systemd being sloppy and stubborn about compatibility and fixing bugs. I could be wrong about that.
    - cthalupa 9y ago
      Linus is generally very specific when he talks about things breaking userspace - changes to the kernel should not make things that work in userspace stop working. systemd doesn't really have the power to completely break userspace in the manner Linus refers to, though it certainly has the power to break a system. (One of my favorites was when a systemd update shut down dhclient but did not restart it, so once dhcp leases expired, servers lost connectivity. It was fun seeing several thousand machines go offline all at once. "Fun.")
      - vidarh 9y ago
        But Linus wasn't the one who wrote about breaking userspace here, so Linus' use of that term is irrelevant.
        otterley 9y ago
        It's a term of art -- one defined by Linus and the kernel team over the past 25+ years. People who have been involved in one way or another with kernel development know what it means, and it makes little sense to redefine it here.
hueving 9y ago
Userspace programs that others frequently depend on the behavior of can easily break userspace. Look how many things break when you change ps or ls out with another tool.

SwellJoe 9y ago

"What did you mean by this? It seems like a complete nonsense statement in the context of user space breakage of the form the kernel is responsible for." Does it? systemd is the init, the service manager, the interface to D-bus (and kernel devs had a bit of a tussle with the systemd devs about kdbus), the logging interface of most services (possibly including kernel logs), etc. systemd interacts with both the kernel directly (as the system init, as one interface to cgroups and namespaces, etc.) and with users (as everything else it does). I like it, but I understand the Borg accusations. "The main clash between the kernel maintainers and the systemd maintainers was over systemd reading the kernel argv in an error prone way to trigger debug information." Searching the LKML for systemd seems to indicate otherwise. It seems like there have been a few scuffles over the years. I don't subscribe to the LKML or read it religiously and haven't for many years, so I'm mostly guessing based on context, but the context seems clear to me. Again, I ask, if not systemd, then which init is Linus talking about?

cthalupa 9y ago
(Disclaimer: I hate systemd) The issue isn't him not knowing what systemd is, or not knowing that that is the init system Linus is talking about. He is aware of both. His issue is with your claim that systemd has broken userspace. You haven't seemed to provide any evidence of this being the case.
- SwellJoe 9y ago
  We may simply be using different terminology. systemd has had bugs (a lot of them), many of which impacted the system at a high level (being the init and everything else), sometimes due to ineractions with the kernel, sometimes due to interactions with other parts of the system. Perhaps others wouldn't call that "userspace", I dunno. I figure if it affects users trying to run software it's "userspace". But, I'm happy to take the "broke userspace" assertion back if you don't like the term. Let's just say systemd has had a lot of bugs, sometimes stupid ones, and sometimes stubbornly held on to despite kernel devs or other devs asking for changes. I would hope we're not arguing about whether systemd has had an exciting number of bugs and compatibility issues (I think we can all agree on that, even if we like systemd). I inferred a bunch from my recollection of how the LKML has talked about systemd in the past. I assumed Linus was talking about systemd and that when he says he doesn't trust it, it was about systemd being sloppy and stubborn about compatibility and fixing bugs. I could be wrong about that.
  - cthalupa 9y ago
    Linus is generally very specific when he talks about things breaking userspace - changes to the kernel should not make things that work in userspace stop working. systemd doesn't really have the power to completely break userspace in the manner Linus refers to, though it certainly has the power to break a system. (One of my favorites was when a systemd update shut down dhclient but did not restart it, so once dhcp leases expired, servers lost connectivity. It was fun seeing several thousand machines go offline all at once. "Fun.")
    - vidarh 9y ago
      But Linus wasn't the one who wrote about breaking userspace here, so Linus' use of that term is irrelevant.
      - otterley 9y ago
        It's a term of art -- one defined by Linus and the kernel team over the past 25+ years. People who have been involved in one way or another with kernel development know what it means, and it makes little sense to redefine it here.

hueving 9y ago

Userspace programs that others frequently depend on the behavior of can easily break userspace. Look how many things break when you change ps or ls out with another tool.