6 ms·

No, performance wasn't the main reason (although that was a big part), it was mainly about race conditions. If userspace implements the bus, then only the half

by blucaz 2y ago

No, performance wasn't the main reason (although that was a big part), it was mainly about race conditions. If userspace implements the bus, then only the half of userspace that comes up after the daemon can use it. Having a reliable IPC mechanism that is available from the moment PID1 is started was the goal. Sadly that was rejected, and Bus1 was too, because apparently it's really bad to have IPC primitives in the kernel, can't have that. Then of course 6 months later Google showed up with a few wheelbarrows of cash and Binder, and strangely all such objections evaporated and it was merged without a peep. Funny how these things go.

p_l 2y ago
Binder predated (significantly![1] Depending on how you count, it predated D-Bus itself[2]) both Bus1 and kdbus projects, and unlike either of them included some extra features for more efficient IPC (like mentioned by me elsewhere ability to pass CPU quanta from caller to callee and back). Making it available from before init formed properly was, quite possibly, considerable part of why it never got merged. Kernel team had spent significant amount of work pushing out things to userland for cases like configuration et al. There's possible issue of applications failing when non-kernel-managed resource goes away, but honestly that's going to be a problem even for handling loss of service on the other end of the bus, too. Funny thing, IIRC, ultimately both kdbus and bus1 had same userland requirements as binder does, which is userland component to set it up and IIRC provide management information too. [1] Binder was mainlined (as experimental, but present in mainline) code in 2012, and made it into stable in 2015. kdbus started unnanounced development the same year, and was proposed for inclusion in 2014 [2] OpenBinder which became Android Binder had 1.0 release in 2005, a year before D-Bus' initial release. And that's not counting original Binder, which shipped for the first time to public in 1995
- blucaz 2y ago
  By "making it available" it doesn't necessarily mean a fully-working, configured broker, but only having enough working primitives that you can bring up userspace without races, with requests that can immediately be accepted, even if not answered until a bit later. The stuff that we currently just cannot do with D-Bus, and that we have to reinvent protocols for. > Binder predated both Bus1 and kdbus projects It's not about when they started, it's about when they got merged/rejected. One got rejected because "ipc in kernel is bad", and some months later the other was merged because "ipc in kernel is good". One rule for thee...
  - p_l 2y ago
    That's my point: Binder got merged before kdbus started development. Also, I still don't see what kind of races you're getting other than having an init system too stupid to handle ordering for applications too stupid to handle graceful connections. (Looking at last version of kdbus docs, the main coherent argument about races is relevant only to how Unix sockets can't pass around authenticated metadata along the message)
    - blucaz 2y ago
      > That's my point: Binder got merged before kdbus started development. It didn't, it was merged in 2015, a year after or so. No, staging doesn't count, it's a dumping ground for all sort of things that do not see the light of day. > Also, I still don't see what kind of races Just because you don't see it, it doesn't mean it's not there. Do some research and you'll see it.
      - p_l 2y ago
        > It didn't, it was merged in 2015, a year after or so. No, staging doesn't count, it's a dumping ground for all sort of things that do not see the light of day. kdbus didn't even make it into staging. Project mainline put in some serious work to get where it got. And quite probably part of it going better was not insisting on becoming mandatory solution for everyone. If anything, it might have been less "wheelbarrows of cash" and more conflicts involving kdbus principal developer and Linus. > Just because you don't see it, it doesn't mean it's not there. Do some research and you'll see it. The kdbus docs could do better job declaring why it's needed then.
        blucaz 2y ago
        > kdbus didn't even make it into staging. Project mainline put in some serious work to get where it got. > > And quite probably part of it going better was not insisting on becoming mandatory solution for everyone. If anything, it might have been less "wheelbarrows of cash" and more conflicts involving kdbus principal developer and Linus. You mean, because it would actually be _used_ somewhere in open source distributions (that is, not just deep inside some de-facto proprietary half-closed-source fork owned by a single mega-corp)? Yeah when things are hidden away in some cupboard in the basement it's much easier not to ruffle feathers. But yeah the LKML is bad today, but back then it was a veritable open-air cesspool > The kdbus docs could do better job declaring why it's needed then. Well, it's dead, so what's the point...

by blucaz 2y ago

p_l 2y ago

Binder predated (significantly![1] Depending on how you count, it predated D-Bus itself[2]) both Bus1 and kdbus projects, and unlike either of them included some extra features for more efficient IPC (like mentioned by me elsewhere ability to pass CPU quanta from caller to callee and back). Making it available from before init formed properly was, quite possibly, considerable part of why it never got merged. Kernel team had spent significant amount of work pushing out things to userland for cases like configuration et al. There's possible issue of applications failing when non-kernel-managed resource goes away, but honestly that's going to be a problem even for handling loss of service on the other end of the bus, too. Funny thing, IIRC, ultimately both kdbus and bus1 had same userland requirements as binder does, which is userland component to set it up and IIRC provide management information too. [1] Binder was mainlined (as experimental, but present in mainline) code in 2012, and made it into stable in 2015. kdbus started unnanounced development the same year, and was proposed for inclusion in 2014 [2] OpenBinder which became Android Binder had 1.0 release in 2005, a year before D-Bus' initial release. And that's not counting original Binder, which shipped for the first time to public in 1995

blucaz 2y ago
By "making it available" it doesn't necessarily mean a fully-working, configured broker, but only having enough working primitives that you can bring up userspace without races, with requests that can immediately be accepted, even if not answered until a bit later. The stuff that we currently just cannot do with D-Bus, and that we have to reinvent protocols for. > Binder predated both Bus1 and kdbus projects It's not about when they started, it's about when they got merged/rejected. One got rejected because "ipc in kernel is bad", and some months later the other was merged because "ipc in kernel is good". One rule for thee...
- p_l 2y ago
  That's my point: Binder got merged before kdbus started development. Also, I still don't see what kind of races you're getting other than having an init system too stupid to handle ordering for applications too stupid to handle graceful connections. (Looking at last version of kdbus docs, the main coherent argument about races is relevant only to how Unix sockets can't pass around authenticated metadata along the message)
  - blucaz 2y ago
    > That's my point: Binder got merged before kdbus started development. It didn't, it was merged in 2015, a year after or so. No, staging doesn't count, it's a dumping ground for all sort of things that do not see the light of day. > Also, I still don't see what kind of races Just because you don't see it, it doesn't mean it's not there. Do some research and you'll see it.
    - p_l 2y ago
      > It didn't, it was merged in 2015, a year after or so. No, staging doesn't count, it's a dumping ground for all sort of things that do not see the light of day. kdbus didn't even make it into staging. Project mainline put in some serious work to get where it got. And quite probably part of it going better was not insisting on becoming mandatory solution for everyone. If anything, it might have been less "wheelbarrows of cash" and more conflicts involving kdbus principal developer and Linus. > Just because you don't see it, it doesn't mean it's not there. Do some research and you'll see it. The kdbus docs could do better job declaring why it's needed then.
      - blucaz 2y ago
        > kdbus didn't even make it into staging. Project mainline put in some serious work to get where it got. > > And quite probably part of it going better was not insisting on becoming mandatory solution for everyone. If anything, it might have been less "wheelbarrows of cash" and more conflicts involving kdbus principal developer and Linus. You mean, because it would actually be _used_ somewhere in open source distributions (that is, not just deep inside some de-facto proprietary half-closed-source fork owned by a single mega-corp)? Yeah when things are hidden away in some cupboard in the basement it's much easier not to ruffle feathers. But yeah the LKML is bad today, but back then it was a veritable open-air cesspool > The kdbus docs could do better job declaring why it's needed then. Well, it's dead, so what's the point...