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Comment by teamhappy | Hacker News Reader

Have a look at FreeBSD's linuxulator. It basically maps syscalls (and a bunch of other stuff) from one OS to another. Alexander Leidinger has written a whole lot of blog posts about it - this one's a good start: http://www.leidinger.net/blog/2010/10/27/the-freebsd-linuxul...

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Is there a source for this being a syscall emulation layer and not some kind of colocation of the linux kernel in a subsystem somehow?

The latter would be much more interesting to me, since what I really want out of "running linux on my desktop" is for it to actually act like the linux machines my code is targeting, and I'm dubious that a syscall layer will achieve that to the degree I want.

A good few years ago now I used to use a project called cooperative Linux that was like what you describe - a user mode Linux kernel running as a service in windows.

Yeah there were actually a couple of projects along this line at various points, but they always suffered in various ways from not being well integrated into the system. What you really want is for the colocated kernel to have first class access to some basic things about the primary kernel (like file systems -- including page caching and networking) so they're not going through an expensive and awkward translation layer.

Cygwin and things like colinux exist on opposite ends of that awkward divide, but something officially supported by the OS could maybe straddle it better.

I feel it is related to Windows Server container. Maybe Ubuntu works like a Docker container on Windows.

There was also another project I worked with a while back called LBW (http://cowlark.com/lbw/) which allowed some unmodified Linux binaries to run on windows using Internix and some really neat syscall handler trickery.

Also the more recent https://github.com/wishstudio/flinux

One of my coworkers is from MS and worked on the Android apps on Windows project. This comes out of that cancelled work: It's a full implementation of Linux syscalls in user mode that registers a driver to perform kernel-mode tasks on behalf of the subsystem. The NT kernel has always been fairly agnostic and not tied specifically to Win32; it originally had an OS/2 text-mode and POSIX subsystem in addition to Win32. The NT kernel even uses a Unix-like "\\?\" root filesystem where disks, kernel objects, sockets, etc are mounted.

From what I can gather Microsoft is paying Canonical to help with a few user-mode bits and the Windows apt-get stuff uses the official Canonical sources.

As I said to him: "NT is the only major OS I know of that has always had personality subsystems. Cutler’s vision finally pays off after 3 decades of waiting"

I love your last paragraph. Exactly what I was thinking. NT Subsystems were its party trick and its taken far too long for them to be introduced on the grand stage. I bet Dave Cutler is smiling his face off!

Thankyou for this concise summary. Much clearer now.

Close, except ...

There is NO Windows "apt-get stuff" - it's just apt-get. From Ubuntu.

> "NT is the only major OS I know of that has always had personality subsystems."

In what way is a "subsystem" different than a "library" or a "process" or a "driver" (if it runs in kernel space)?

Any process can use the native API. What's special about a "subsystem"?

What was his vision?

I know that Dave Cutler was heavily involved in designing NT, and was earlier the same with DEC VMS. (Had read the book Inside Windows NT.)

But don't know what vision you refer to. Was it about the personality subsystems?

Before leaving for MS, Cutler worked on an OS codenamed "Mica" which ran on top of an architecture named PRISM (which was a predecessor to the Alpha). The idea behind Mica was that it was a microkernel which hosted VMS and Unix personalities on top.

It is widely claimed and believed that when he moved with his team to MS that he reimplemented Mica as the NT kernel. http://www.textfiles.com/bitsavers/pdf/dec/prism/mica/

> "Cutler’s vision finally pays off after 3 decades of waiting."

Quite!

But only because the Interix-derived POSIX subsytem was, and is, little-known and vastly underappreciated. Had it been better known, the payoff might have come a decade or more sooner. There are a fair number of questions being asked now, about the new Linux subsystem, where the answer is "No; but the old POSIX subsystem had that.".

* Does it support pseudo-terminals? No, according to the demonstration video; but the old POSIX subsystem did. (https://news.ycombinator.com/item?id=11415843)

* Does it let you kill Win32 processes? No; but the old POSIX subsystem did. (https://news.ycombinator.com/item?id=11415872)

* Does it support managing daemons? No; but the old POSIX subsystem did. (https://news.ycombinator.com/item?id=11416376)

* Does it support GUI programs? No (say the people behind it themselves, although I suspect that it could run X clients); but the old POSIX subsystem did. (https://news.ycombinator.com/item?id=11391961) (https://technet.microsoft.com/en-gb/library/bb463223.aspx)

I remember having a Microsoft developer (I'm afraid I forget her name — Six?) come and visit us several years ago to demonstrate the then-new SFU 3.0.

Seeing her send SIGSTOP to a running MSWORD.EXE process and observe it stop updating its window in response to expose events was splendid. :-)

From linux(4):

     The linux module provides limited Linux ABI (application binary inter-
     face) compatibility for userland applications.  The module	provides the
     following significant facilities:

     +o	 An image activator for	correctly branded elf(5) executable images

     +o	 Special signal	handling for activated images

     +o	 Linux to native system	call translation

     It	is important to	note that the Linux ABI	support	it not provided
     through an	emulator.  Rather, a true (albeit limited) ABI implementation
     is	provided.

https://www.freebsd.org/cgi/man.cgi?query=linux&apropos=0&se...

"Mapping syscalls from one OS to another" was really just an example to give the OP an idea of how this sort of thing works without a VM.

Edit: Nevermind then

I wasn't asking about freebsd (I've used that, even!), I was asking about this new thing on Windows and whether there's been official word that it is indeed the same sort of thing. Looks like it is indeed this sort of thing, though.

http://blog.dustinkirkland.com/2016/03/ubuntu-on-windows.htm...

Thanks, this is what I was actually looking for. :)

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