Trying to build L4 on NixOS

Adam Lackorzynski adam at
Fri Mar 31 00:30:38 CEST 2017

On Wed Mar 29, 2017 at 23:14:11 +0200, Mateusz Czaplinski wrote:
> On Sun, Mar 26, 2017 at 11:51 PM, Adam Lackorzynski <
> adam at> wrote:
> > You need to build l4 for L4Linux as L4Linux also requires L4Re.
> >
> Hm; so I'm still not exactly clear about how this is structured in the repo
> and how it builds together. Specifically: I seem to have built the project
> contained in the l4linux subdir of the l4re-snapshot-2016082114 archive;
> does it reach from l4linux/ to ../l4re/ and ../kernel/fiasco/ in process,
> through the makefiles from inside l4linux/ ? It didn't complain about any
> missing binaries, even though I didn't give it access to any precompiled
> l4re or fiasco libs before "make".

No, you need to give that info. I think on your L4Linux build ARCH=x86
was somehow set so it just build a normal Linux kernel.

> I seem to have replaced my old kernel with the result, and it went, ummm...
> suspiciously smooth... am I really running on Fiasco.OC+L4Linux? Or did I
> just accidentally recompile a regular kernel, and just renamed a few
> strings in it so that `uname --all` can now wink and say "huh huh, yeah
> sure, 4.7-l4, nod nod", but in reality I just tricked myself in an overly
> complicated way?

The top-level Makefile sets this "-l4" suffix, despite what version
you're actually building.

> Is there some means by which I could test/verify that yes indeed, I am now,
> or am not, on L4 full and proper in my VM? Some L4 API, or some other "one
> weird trick" I can try, that can only work with L4 (vel Fiasco)? From
> inside or outside (I'm doing it in Hyper-V)? I've put down the some

The build system won't just overwrite your host system, so it
did not do that. (Did you bulid as root? Don't do that!)
Further, some setup and configuration is needed.

Since L4Linux pretty adopted to L4Re you could for example check dmesg
and see some L4-specific lines there. Or you could check


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