Linux compatibility with more than one Linux installed?

Doug Barton dougb at
Tue Dec 13 21:59:25 UTC 2011

On 12/06/2011 05:45, RW wrote:
> On Tue, 6 Dec 2011 06:29:03 -0600
> Zhihao Yuan wrote:
>> On Tue, Dec 6, 2011 at 6:21 AM, RW <rwmaillists at> wrote:
>>> On Tue, 6 Dec 2011 04:54:18 -0600
>>> Zhihao Yuan wrote:
>>>> Not really. The actual thing is, linuxulator is a Linux kernel
>>>> running as a FreeBSD kernel module. The only thing FreeBSD kernel
>>>> do is to identify the Linux program and to pass it to the Linux
>>>> kernel. To the Linux programs inside a GNU chroot enviroment, they
>>>> think they are running inside a Linux box and actually they are
>>>> running inside a Linux box.
>>> Are you sure about that? I was under the impression that it was a
>>> fairly thin emulation layer on top of the FreeBSD kernel. Has
>>> something changed?
>> To Linux program, there is no "emulation layer". This technology
>> should be called "extended ELF lookup table", and has nothing to do
>> with emulation.
> It's not emulation in the narrow sense that vmware is emulation and
> wine isn't, but it certainly is emulation within the normal sense or the
> word. My dictionary defines emulate as "imitate zealously".

It's not emulation, in fact it's much more like wine. We have
traditionally referred to it as "Linux binary compatibility" rather then
emulation, since the Linux syscalls are actually implemented by the
FreeBSD kernel.

> But what I was getting at was the statement "linuxulator is a Linux
> kernel running as a FreeBSD kernel module" which I'm guessing now you
> didn't mean literally.

That's not true in the sense that it's a separate process, but it is
true in a sense, see above.




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