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It seems this article badly needs to be updated in light of Ubuntu on Windows. Here's a link from 2016 instead of 2010. https://insights.ubuntu.com/2016/03/30/u

by grennis 10y ago

It seems this article badly needs to be updated in light of Ubuntu on Windows. Here's a link from 2016 instead of 2010. https://insights.ubuntu.com/2016/03/30/ubuntu-on-windows-the-ubuntu-userspace-for-windows-developers/ https://insights.ubuntu.com/2016/03/30/ubuntu-on-windows-the...

diyorgasms 10y ago
Except this is an article about Interix. Correct me if I'm wrong, but Microsoft seems to have discarded this particular technology entirely and started over fresh with Ubuntu on Windows.
toyg 10y ago
IIUC the new Ubuntu-on-Windows stuff is a different take, reusing some of Interix but diverging substantially from the old implementation. EDIT Source[1]: "Over time these [Interix] subsystems were retired. However, since the Windows NT Kernel was architected to allow new subsystem environments, we were able to use the initial investments made in this area and broaden them to develop the Windows Subsystem for Linux." [1] https://blogs.msdn.microsoft.com/wsl/2016/04/22/windows-subsystem-for-linux-overview/ https://blogs.msdn.microsoft.com/wsl/2016/04/22/windows-subs...
- baq 10y ago
  great link, a must-read for anyone interested in how they did it.
- quietplatypus 10y ago
  Great article! I'm not too familiar with OS as a subject, but is the separation between user and kernel mode similar to high-level language versus assembly; i.e., the approach they took was to emulate the Linux kernel, which is sort of like a virtual machine. But I imagine emulating a kernel is harder, right? Because of all the stuff that goes on? And in general, would kernel emulation be a performant approach for running userspace of any OS in any other OS?
  - gpvos 10y ago
    It's more like Wine: the code runs directly on the hardware, but there is an extra layer that emulates the system calls. Except that in this case, the emulation has a lot of supporting code in a kernel driver, something that Wine doesn't have. (Actually, for Win32 programs there is also such a layer, however that layer and the NT kernel were designed together from the start, so it can be pretty thin.)
    - WorldMaker 10y ago
      It's an interesting fuzzy gray boundary between the Ubuntu on Windows and "emulation". It's still built as an NT sub-system (like Interix was), and it's still the NT kernel ultimately in charge of everything. The difference seems to be the NT kernel implementing the generic POSIX standard versus the NT kernel implementing the specific system calls of the Linux kernel. So on one hand it is an emulation because there are specific real world binary behaviors (and quirks and bugs) it's trying to replicate, versus implementing standards from a specification document, but on the other hand, it still seems to be the NT Kernel doing NT Kernel things.
      - quietplatypus 10y ago
        I guess the line is a bit blurry, especially when you factor in fast virtualization techniques that involve running emulated instructions directly :)
    - quietplatypus 10y ago
      Gotcha. Thanks for the explanation! Which would you say was harder, Wine or this? It seems like Wine should have been harder since the NT kernel was designed with multiple userspaces in mind...
      - gpvos 10y ago
        Wine is basically reverse engineering a badly documented black box. On the other hand, even though the Linux source is available, Microsoft programmers probably aren't allowed to look at it to prevent their code from becoming a derivative GPL'ed work.
lmm 10y ago
It's a timely reminder for anyone getting excited about Ubuntu on Windows that Microsoft had a working system for doing that, only to slowly run it into the ground. I'd have a lot more respect for the new system if they'd revived Interix/SFU/SUA rather than releasing a different, incompatible replacement.
- amenod 10y ago
  Exactly, couldn't say it better! MS has a history of decisions which were meant to strangle the competition, one way or the other. Interoperability was never one of their strong suits.
- yuhong 10y ago
  I think the point is to allow Linux binaries to be used without a recompile, which saves MS most of the cost of maintaining binaries for it.
  - chungy 10y ago
    Which is the key. Plenty of ISVs make Linux binaries, but nobody was interested in Interix binaries.
    - WorldMaker 10y ago
      Indeed. I think you can see this in some of the history in this article: Interix was "POSIX compatible", but essentially its own OS, like compiling for Linux versus BSD. So someone had to maintain binary builds of GNU tools for Interix and thus you ended up with the large "Tools" distribution of user space binaries. Ultimately, "Tools" was its own Unix distribution that was subtly incompatible with any other Unix distribution. Even today on Linux you still see a lot of the headaches in the subtle binary incompatibilities across Linux distributions. The amazing thing with Ubuntu on Windows is that user space is the same Ubuntu distribution of user space tools as on Linux. That lessens the maintenance burden of the User Space considerably as Canonical is already actively maintaining that distribution, and will continue to actively maintain that distribution, and that there are a considerable number of users of that distribution on Linux already and a considerable ecosystem of third parties building for that distribution. Those are definitely the missing pieces that Interix never had and makes this "Son of Interix" that is Ubuntu on Windows much more interesting.

by grennis 10y ago

diyorgasms 10y ago

Except this is an article about Interix. Correct me if I'm wrong, but Microsoft seems to have discarded this particular technology entirely and started over fresh with Ubuntu on Windows.

toyg 10y ago

IIUC the new Ubuntu-on-Windows stuff is a different take, reusing some of Interix but diverging substantially from the old implementation. EDIT Source[1]: "Over time these [Interix] subsystems were retired. However, since the Windows NT Kernel was architected to allow new subsystem environments, we were able to use the initial investments made in this area and broaden them to develop the Windows Subsystem for Linux." [1] https://blogs.msdn.microsoft.com/wsl/2016/04/22/windows-subsystem-for-linux-overview/ https://blogs.msdn.microsoft.com/wsl/2016/04/22/windows-subs...

baq 10y ago
great link, a must-read for anyone interested in how they did it.
quietplatypus 10y ago
Great article! I'm not too familiar with OS as a subject, but is the separation between user and kernel mode similar to high-level language versus assembly; i.e., the approach they took was to emulate the Linux kernel, which is sort of like a virtual machine. But I imagine emulating a kernel is harder, right? Because of all the stuff that goes on? And in general, would kernel emulation be a performant approach for running userspace of any OS in any other OS?
- gpvos 10y ago
  It's more like Wine: the code runs directly on the hardware, but there is an extra layer that emulates the system calls. Except that in this case, the emulation has a lot of supporting code in a kernel driver, something that Wine doesn't have. (Actually, for Win32 programs there is also such a layer, however that layer and the NT kernel were designed together from the start, so it can be pretty thin.)
  - WorldMaker 10y ago
    It's an interesting fuzzy gray boundary between the Ubuntu on Windows and "emulation". It's still built as an NT sub-system (like Interix was), and it's still the NT kernel ultimately in charge of everything. The difference seems to be the NT kernel implementing the generic POSIX standard versus the NT kernel implementing the specific system calls of the Linux kernel. So on one hand it is an emulation because there are specific real world binary behaviors (and quirks and bugs) it's trying to replicate, versus implementing standards from a specification document, but on the other hand, it still seems to be the NT Kernel doing NT Kernel things.
    - quietplatypus 10y ago
      I guess the line is a bit blurry, especially when you factor in fast virtualization techniques that involve running emulated instructions directly :)
  - quietplatypus 10y ago
    Gotcha. Thanks for the explanation! Which would you say was harder, Wine or this? It seems like Wine should have been harder since the NT kernel was designed with multiple userspaces in mind...
    - gpvos 10y ago
      Wine is basically reverse engineering a badly documented black box. On the other hand, even though the Linux source is available, Microsoft programmers probably aren't allowed to look at it to prevent their code from becoming a derivative GPL'ed work.

lmm 10y ago

It's a timely reminder for anyone getting excited about Ubuntu on Windows that Microsoft had a working system for doing that, only to slowly run it into the ground. I'd have a lot more respect for the new system if they'd revived Interix/SFU/SUA rather than releasing a different, incompatible replacement.

amenod 10y ago
Exactly, couldn't say it better! MS has a history of decisions which were meant to strangle the competition, one way or the other. Interoperability was never one of their strong suits.
yuhong 10y ago
I think the point is to allow Linux binaries to be used without a recompile, which saves MS most of the cost of maintaining binaries for it.
- chungy 10y ago
  Which is the key. Plenty of ISVs make Linux binaries, but nobody was interested in Interix binaries.
  - WorldMaker 10y ago
    Indeed. I think you can see this in some of the history in this article: Interix was "POSIX compatible", but essentially its own OS, like compiling for Linux versus BSD. So someone had to maintain binary builds of GNU tools for Interix and thus you ended up with the large "Tools" distribution of user space binaries. Ultimately, "Tools" was its own Unix distribution that was subtly incompatible with any other Unix distribution. Even today on Linux you still see a lot of the headaches in the subtle binary incompatibilities across Linux distributions. The amazing thing with Ubuntu on Windows is that user space is the same Ubuntu distribution of user space tools as on Linux. That lessens the maintenance burden of the User Space considerably as Canonical is already actively maintaining that distribution, and will continue to actively maintain that distribution, and that there are a considerable number of users of that distribution on Linux already and a considerable ecosystem of third parties building for that distribution. Those are definitely the missing pieces that Interix never had and makes this "Son of Interix" that is Ubuntu on Windows much more interesting.