@cas I figured this out for myself - sorry I should have just re read all instructions again in the first place.

I changed the lines:

"# define the toolchain and target names
TOOLCHAIN_NAME="toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16"
TARGET_NAME="target-mipsel_24kc_musl-1.1.16"

in xCompile.sh

to :

"# define the toolchain and target names
TOOLCHAIN_NAME="toolchain-mipsel_24kc_gcc-7.3.0_musl"
TARGET_NAME="target-mipsel_24kc_musl"

and the example C gipoRead compiled fine and runs on my board.

@cas Thanks Cas - I set up a new 120GB SSD specifically for this 'machine' so apart from the fresh install of Ubuntu there is nothing else on the disk - i can see docker in var/lib - so with the container resizing I should be fine.

I got a successful compile of the image on my second attempt.

However, when I try to compile the example code from:

https://github.com/OnionIoT/c-cross-compile-example.git

I get the following error

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

I note that the git directory I cloned from hasn't been touched for 2 years so this example is likely out of date. When I look in /root/source/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.16/ there is no bin directory. I found a bin directory with the mipsel-openwrt-linux-gcc in /root/source/staging_dir/toolchain-mipsel_24kc_gcc-7.3.0_musl but I have no idea what to edit to ensure that this file is used - it doesn't appear to be the makefile ?

@cas Thanks - How do I do that; should I have added some option when I installed Docker ?

@crispyoz Thanks - I've got serial console working so I have some option if I brick it

@Janus-Sanders Looking at this post on Stack Overflow
https://stackoverflow.com/questions/52848004/how-to-increase-docker-disk-image-size-in-ubuntu
it appears that there is no way and no need to increase the container size. BTW I'm running Ubuntu 18.04 with extfs filesystem. Hope this makes sense ?

@Janus-Sanders @cas

Hi I've been stuck all day trying to set the container size either by increasing the container size limit: https://bobcares.com/blog/docker-container-size/
or using the --storage-opt size=40G option.

I haven't had any success and am guessing that there must be a simple way to do this that I haven't found ?

@cas Thanks for this - I've followed your instructions - it looks like they contain detail missing from the Omega tutorial on cross-compilation so you have probably saved alot of head scratching.

It looks like I have alot to learn and feeling a bit out of my depth.

Presumably the firmware revision should match that on my board ?

@crispyoz @Janus-Sanders Thanks for your replies.

@crispyoz - I guess I will only find this out once I try ? I only need one module from OpenCV - not the complete library so will not need the dependencies. As far as I can see you can specify this at build:
https://stackoverflow.com/questions/25594003/build-specific-modules-opencv

@Janus-Sanders Do you know if this Docker Image;
https://hub.docker.com/r/onion/omega2-source/
will work for my Omega2 Pro;
https://onion.io/announcing-the-new-omega2-pro/

Best Wishes,

Ed

Hi Janus

Thanks for your reply.

Definitely some confusion - I'm by no means an expert !

I have now read; https://docs.onion.io/omega2-docs/c-compiler-on-omega.html and https://docs.onion.io/omega2-docs/cross-compiling.html#cross-compiling.

My understanding from these articles and your reply is that if I want to write a program in C++ that uses the OpenCV library then I should write AND cross-compile that program on a LEDE build system installed on a PC. I then copy the compiled program to my Onion. When I then run that program on my Onion it will then use the compiled library binaries already installed on my Onion by opkg.

Does this make more sense ?

Thanks for your help.

Ed

I have tried to install OpenCV using opkg (opkg install opencv).

No errors were reported during install but when I look on the system I can only find can only find library (.so.) files and no header (.h) files.

I cannot compile any code.

I don't understand the package manager - is the code from this ready to run (as a return that the package has installed would imply) or do packages need to be compiled ?

I have found a couple of threads on here discussing OpenCV but no conclusion.