Hello, world!

[Nobody III]

You're welcome. Glad I could help.

>From the list, most of those functions are implemented in libc, but
overridden in Noux. Please note that Noux provides a system call interface,
while libc doesn't normally use or require that, but instead uses Genode's
library function calls more directly. The execve function isn't implemented
except in Noux AFAIK, but could possibly be implemented without a special
environment.

First, if you haven't already, you should follow the instructions for
creating a build directory, then build and run one of the many scenarios,
e.g. run/demo.

For compiling a simple C application, you first need to have/pick a repos
subdirectory. To start out, you could use one of the ones provided, e.g.
repos/gems. You then need to create a subdirectory for your application
somewhere inside repos/[your repo]/src, e.g. repos/gems/app/simple_c_app.
After that, you need to write your C code and place it in a file in that
directory. Then write a makefile named target.mk in the same directory with
the C code. The makefile should look something like the following:

TARGET = simple_c_app
SRC_C = main.c
LIBS   = base libc posix

When you have your source file(s) and makefile written, and your repo
directory added to etc/build.conf in your build directory, you should be
able to compile it using "make app/simple_c_app".

If you want to run your app, you need to write a run script. Creating a
good run script for testing your app might be difficult, but you can start
with something simple. You can start by copying repos/gems/run/pipe.run and
modifying that.

For most of this, I'd recommend looking at the pipe example by Emery
Hemingway, as found in repos/gems/src/app/pipe, and the aforementioned run
script. Please note that the pipe example uses C-style C++. If you want to
use pure C, be sure to use the variable SRC_C in the makefile rather than
SRC_CC.

I hope this helps.

On Mon, Nov 19, 2018 at 8:42 AM Wouter van Oijen <
wouter.van.oijen at technolution.nl> wrote:

> Hi "Nobody III" ;-)
>
> Thanks for your reaction! I have some follow-up questions though:
>
> >
> > Port files are only necessary to download external code.
> >
> Okay, thanks for clearing that up :-)
>
>
> > I'm not sure about your second question. In particular, noux was
> intended exclusively for ported software. At this point, its main purpose
> is to emulate the fork() system call. For software that doesn't require
> that, I'd recommend just using libc instead. Noux also isn't designed for
> code isolation within a single noux instance, so that might be an issue as
> well.
> >
>
> Hmm, now I'm a bit confused. I was under the impression that Noux was
> necessary for a lot more than just fork(), like things as file access
> and networking as well. For example, at
> https://genode.org/documentation/release-notes/11.02 it is mentioned
> that "without the right environment that presents the program the
> needed UNIX functionality, those [unmodified, recompiled] programs
> won't do much. This leads us to the Noux execution environment." And
> also "Currently the Noux execution environment implements the
> following system calls: getcwd, write, stat, fstat, fcntl, open,
> close, dirent, fchdir, read, and execve."
>
> Are these functions now implemented in libc and can they work without
> Noux? In general, could I then recompile any Unix application that
> doesn't use fork(), and run it as a Genode component?
>
> If not, what would I need to do compile a simple standard-C
> application that writes some data to a file and then reads from that
> file?
>
> I do understand that the code isolation is limited to isolation
> between different Noux instances and not within the application
> itself. This is fine for our demo, but thanks for pointing it out.
>
> > There are plenty of code isolation examples available, and we can help
> you more if you tell us more about what you're trying to do. Then we can
> give you much better advice on what libraries and RPC interfaces to use.
> For example, if you want to separate a login screen's GUI from the password
> verification and login code, I'd recommend using the Report interface
> and/or the File_system interface.
> >
>
> I'm currently trying to get existing software (specifically: a
> Mosquitto broker) to build and run in Genode, so I'm not using the
> Genode interfaces. However, since the Genode build flow is still a big
> mystery for me, I was first trying to build and run some basic
> examples... Hence the above questions.
>
> Kind regards,
> Wouter
>
> _______________________________________________
> Genode users mailing list
> users at lists.genode.org
> https://lists.genode.org/listinfo/users
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