Cross Compiling on the Omega2

[MarshalllGG]

Hi all,
I'm really new in this world and I'm moving my first steps with the omega2, the hardware I'm trying to use is: Omega2+, Expansion Dock, OLED display

First thing I followed the guide First Time Setup, and all went good
Then I followed the Cross Compiling Guide step by step

I downloaded the Docker for Linux Ubuntu 20.04 selecting focal --> pool --> stable ---> amd64

and, unfortunately, I had a problem in the step:

docker pull onion/omega2-source

The error I got is the following:

Using default tag: latest
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.40/images/create?fromImage=onion%2Fomega2-source&tag=latest: dial unix /var/run/docker.sock: connect: permission denied

Can someone help me? Thank you very much

EDIT:
I solved this problem, but running the last command

make

i'm getting this error:

Collecting package info: done
WARNING: Makefile 'package/feeds/onion/transmission-console-app/Makefile' has a dependency on 'Onion-Console', which does not exist
WARNING: Makefile 'package/feeds/onion/transmission-console-app/Makefile' has a dependency on 'transmission-daemon', which does not exist
WARNING: Makefile 'package/feeds/onion/zeromq/Makefile' has a build dependency on 'libuuid', which does not exist
make[2]: Entering directory '/root/source/scripts/config'
conf.c: In function 'check_stdin':
conf.c:78:3: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_("aborted!\n\n"));
^~~~~~
conf.c:79:3: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_("Console input/output is redirected. "));
^~~~~~
conf.c:80:3: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_("Run 'make oldconfig' to update configuration.\n\n"));
^~~~~~
conf.c: In function 'conf_askvalue':
conf.c:90:3: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_("(NEW) "));
^~~~~~
conf.c: In function 'conf_choice':
conf.c:291:5: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_(" (NEW)"));
^~~~~~
conf.c: In function 'check_conf':
conf.c:439:6: warning: format not a string literal and no format arguments [-Wformat-security]
printf(_("\n* Restart config...\n*\n"));
^~~~~~
conf.c: In function 'main':
conf.c:620:6: warning: format not a string literal and no format arguments [-Wformat-security]
_("\n*** The configuration requires explicit update.\n\n"));
^
conf.c:674:4: warning: format not a string literal and no format arguments [-Wformat-security]
fprintf(stderr, _("\n*** Error during writing of the configuration.\n\n"));
^~~~~~~
conf.c:678:4: warning: format not a string literal and no format arguments [-Wformat-security]
fprintf(stderr, _("\n*** Error during update of the configuration.\n\n"));
^~~~~~~
conf.c:689:4: warning: format not a string literal and no format arguments [-Wformat-security]
fprintf(stderr, _("\n*** Error during writing of the configuration.\n\n"));
^~~~~~~
make[2]: Leaving directory '/root/source/scripts/config'
time: target/linux/prereq#0.09#0.01#0.10
Checking 'rsync'... ok.
WARNING: your configuration is out of sync. Please run make menuconfig, oldconfig or defconfig!
make[1] world
make[2] tools/compile
make[3] -C tools/flock compile
make[3] -C tools/sed compile
make[3] -C tools/patch compile
make[3] -C tools/xz compile
make[3] -C tools/tar compile*

[crispyoz]

@MarshalllGG These are warnings not errors so the make will continue.

[MarshalllGG]

Okay thank you, I solved the problem and the make went good, but going on with my cross compilation:

I wrote the file hello.c

*#include‹stdio.h›

int main()
{
printf("Hello World\n");
printf("We are running a cross-compiled C program on the Omega2!\n");
return(0);
}*

I used this to cross compile (as written in the Onion guide):

/root/source/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/bin/mipsel-openwrt-linux-gcc hello.c -o hello

The error I got is:

bash: /root/source/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/bin/mipsel-openwrt-linux-gcc: Permission denied

I'm on architecture amd64 and the os is linux ubuntu 20.04

Can you help me? Thx

[crispyoz]

@MarshalllGG The error indicates you do not have permission to execute the compiler, try the same command with sudo:

sudo /root/source/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/bin/mipsel-openwrt-linux-gcc hello.c -o hello

When prompted enter the root password.

You shouldn't be running stuff as root on *nix but from your command it seems the source is installed as root.

[MarshalllGG]

Thank you, I tried with sudo and then the command:

this is what i get:

sudo: /root/source/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/bin/mipsel-openwrt-linux-gcc: command not found

Is there an error with the installation of the toolchain?

[crispyoz]

@MarshalllGG Sorry I don't use the docker image I prefer to install on my own Ubuntu 20 system, however I suspect the correct compiler path is:

staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/bin/mipsel-openwrt-linux-gcc

Note that the gcc version is 7.3.0 instead of 5.4.0

[MarshalllGG]

Okay I compiled successfully hello wolrd, now the problem is when I link external libraries..
I linked with this syntax:

root@229a08e06724:~/source/projects/c-cross-compile-example# sh xCompile.sh -buildroot /root/source -lib "oled-exp -ludpsocketlib"

the library I want to use is my own "udpsocketlib.c" and the header file is "udpsocketlib.h" (all in the same directory with makefile and the main of my udpserver.c program

The error I got this time is this:

make: /root/source/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl/bin/mipsel-openwrt-linux-gcc: Command not found
makefile:9: recipe for target 'udpserver' failed
make: *** [udpserver] Error 127

[tjoseph1]

@MarshalllGG

Sorry, I don't use docker either..

To get to know compiling process in detail, would suggest the following book to anyone:
Advanced C and C++ Compiling by Milan Stevanovic

Thanks.

[crispyoz]

@MarshalllGG Maybe you will find this easier if you use Apache Netbeans IDE, take a look at my article on setting up to use with the cross compiler:

https://community.onion.io/topic/4131/setup-netbeans-11-for-c-c-development-cross-compilation/2?_=1628474815438

[MarshalllGG]

@crispyoz
Thank you,
I'm trying to setup netbeans, but when I open 'tools' in the c/c++ I have a different screen:
I Need to setup a ccls configuration (?)

I tried Also a lot to crosscompile my c programs with the Onion's tutorial, but I noticed that also the c-cross-compile-example with gpioRead fails in compilation:

makefile:9: recipe for target 'gpioRead' failed
make *** [gpioRead] Error 127

Do you know if cross compilation is the only method to use the OLED expansion C libraries?

[crispyoz]

@MarshalllGG I can't guess what your netbeans screen looks like so you need to post it.

So we can see what the issue is with your cross-compiling post more of the output.

My crystal ball is in the shop

[MarshalllGG]

@crispyoz

I'm sorry, here's my screen

[crispyoz]

@MarshalllGG Looks like there is some problem with your plugin . Look in Tools Plugins and check you have the correct plugin installed per the attached screen.

[MarshalllGG]

Ye I found also this.

In my netbeans I see this and then I search tools and I get the last screen I posted.

[crispyoz]

@MarshalllGG You need to activate "User Installed Plugins" it is currently inactive.

[MarshalllGG]

Okay @crispyoz thank you very much, I installed successfully Netbeans and seems to be working in the right way.
I need some other tips also because it's the first time I use a tool like this (to compile simple programs I had only textedit and the terminal).

Now I created my C project and in my source folder I have the main, for example a program to display "hello world" on the OLED screen of the omega.

How can I link the oled C libraries in the cross-compilation with NetBeans? Do I have to download them or are stored in the usr/lib folder ?

Thank you another time

[crispyoz]

@MarshalllGG Right click on your project, choose properties, then select Linker on the left and you can configure the path to your libraries in "Additional Library Directories" is you have the build system installed then this would be the path, source/staging_dir/target-mipsel_24kc_musl/usr/lib

Then in the same screen "Libraries", then "Add Library File" and browse the file system to select source/staging_dir/target-mipsel_24kc_musl/usr/lib/libonionoledexp.so

[MarshalllGG]

@crispyoz

Thank you I'm trying now but seems that the libonionoledexp isn't installed, this is the screen:

[crispyoz]

@MarshalllGG Take a look in make menuconfig and ensure you have selected Onion->Libraries->libonionoledexp, if it is not selected, select it then run make

[MarshalllGG]

Same problem
Maybe do I need to compile another time the toolchain?

also searching "oled" no matches found

[crispyoz]

@MarshalllGG From the main menu "Onion" then "Libraries"