...ok, I figure it out (more or less):
There's on open regressed issue on Mono project for this:
https://github.com/mono/mono/issues/9951
I had to switch back to 2018-04 branch on Mono to make it work.
Compiled with openwrt-sdk-18.06.1-ramips-mt76x8_gcc-7.3.0_musl.Linux-x86_64.tar.xz
Cheers!
I think I have ignored that autogen.sh ends with an error around checking shm_open:
checking for inotify_rm_watch with unsigned wd... no
checking for shm_open that works well enough with mmap... configure: error: in `/home/project/mono':
configure: error: cannot run test program while cross compiling
See `config.log' for more details
How to workaround it? Obviously it can not run crosscompiled test on build machine 
@Jackdaw I stuck on setting crosscompiled environment. I mean - after all setup for crosscopile (I used also recent openwrt-sdk-18.06.1-ramips-mt76x8_gcc-7.3.0_musl.Linux-x86_64.tar.xz) BuildMono/bin/mono is build for Ubuntu (not for Omega2). Both BuildHost/bin/mono and BuildMono/bin/mono works on Ubuntu but the latter not works on Omega2 (wrong ELF format). So I suspected that cross-tools are wrongly setup and in the second stage still Ubuntu host tools are used (in /Makefile commands CC = gcc)
I tried your solution with export CC=$CROSS-gcc
and also alising it manually before automake and make but it still build host-platform version 
Any idea how to properly setup cross-toolsets before compiling for ramips-mt76x8 ?
@Theodore-Borromeo any updates on your experience with OpenCV on Onion since 2016?
Cheers!
Pawel
Thanks for sharing this info, very valuable!
Is there a chance to share also some more info regarding your C# projects that you run with this mono (.NET version, environment, compiling, library compatibility issues, etc)?
Would love to hear more on C# on Omega Onion!
I wonder is it achievable to build a .NET app using Visual Studio (.NET Core?) that could handle HTTP requests (Kestrel/WebListener or even HttpServer for non-core), manage Omega GPIO and I2C bus as well as managing other native OpenWRT processes outside the mono (e.g. madplay).
Cheers!
Hi Guys,
First of all - great idea and product! I'am glad I had a chance to support you on kickstarter 
My question - do you have any plans to support Windows 10 IoT Core with Onion2?
https://developer.microsoft.com/en-us/windows/iot/explore/deviceoptions
It would be lovely to have Onion there among Raspeberry Pi, DragonBoard and others...
Warm Regards,
Paul
