Let me start off by saying I consider myself extremely ignorant when it comes to compiling C, Linux, cross-compiling anything, LEDE/OpenWrt, toolchains, and on and on. However, I was finally able to cross-compile the FAAD2 audio decoder to work on the Omega2+. I can't promise that I remember every step I took (there was a lot of trial and error) but I'll do my best to describe what I did to make it happen.

I did this on a Linux Mint system, fyi.

First some resources I found helpful:
FAAD2 source
Using OpenWrt SDK to Build C/C++ Programs
Cross-compile on OpenWRT Wiki
Cross compiling Rust applications for the Omega
WereCatf's source repo

I began by downloading WereCatf's source repo
git clone https://github.com/WereCatf/source omega-sdk
cd omega-sdk

Then I ran make menuconfig and selected Onion Omega2+ from the Target Profile option.
Save the configuration and exit the menu.

Now run make toolchain/install and go watch a movie (or two). Seriously, this step took 3 hours. Also worth noting is that I tried to do this on a mac running Sierra and was not able to get this part to work. Something is weird with the version of pkg-config on OS X.

After you see Frodo hurl the ring into the lava you can come back and extract the FAAD2 source (or whatever you're trying to compile) into the package folder.
Now run make package/faad2-2.7/compile (or whatever the dir to your package is)
You should now be able to find the compiled binary (or whatever you're compiling) in the build_dir directory. In my case I found what I was looking for in build_dir/target-mipsel_24kc_musl-1.1.15/faad2-2.7/common/faad Copy the binary to your Omega and try running it.

Good luck!

Let me start off by saying I consider myself extremely ignorant when it comes to compiling C, Linux, cross-compiling anything, LEDE/OpenWrt, toolchains, and on and on. However, I was finally able to cross-compile the FAAD2 audio decoder to work on the Omega2+. I can't promise that I remember every step I took (there was a lot of trial and error) but I'll do my best to describe what I did to make it happen.

I did this on a Linux Mint system, fyi.

First some resources I found helpful:
FAAD2 source
Using OpenWrt SDK to Build C/C++ Programs
Cross-compile on OpenWRT Wiki
Cross compiling Rust applications for the Omega
WereCatf's source repo

I began by downloading WereCatf's source repo
git clone https://github.com/WereCatf/source omega-sdk
cd omega-sdk

Then I ran make menuconfig and selected Onion Omega2+ from the Target Profile option.
Save the configuration and exit the menu.

Now run make toolchain/install and go watch a movie (or two). Seriously, this step took 3 hours. Also worth noting is that I tried to do this on a mac running Sierra and was not able to get this part to work. Something is weird with the version of pkg-config on OS X.

After you see Frodo hurl the ring into the lava you can come back and extract the FAAD2 source (or whatever you're trying to compile) into the package folder.
Now run make package/faad2-2.7/compile (or whatever the dir to your package is)
You should now be able to find the compiled binary (or whatever you're compiling) in the build_dir directory. In my case I found what I was looking for in build_dir/target-mipsel_24kc_musl-1.1.15/faad2-2.7/common/faad Copy the binary to your Omega and try running it.

Good luck!

@Thomas-Jager have you had any luck?

i too am trying to figure out how to connect to an enterprise network. i've changed just about every configuration option i can think of but i would be willing to bet that whatever package it's using to connect doesn't even support PEAP.

well, shucks...
thanks very much for the reply.
the real problem i'm having is that i'm trying to build some packages from source and installing all the dependencies, etc. fills up the limited space on the device. any suggestions for how to proceed? like, maybe booting from a usb device?
I know @Duane-Morin was working on that here: (https://community.onion.io/topic/1235/does-reboot-not-come-back-for-anybody-else)

Here's what I'm trying to do. I'd like to create a Virtualbox image of the Omega2+ firmware so that I can mess around with it without the fear of bricking my device.
I found this guy: (http://repo.onion.io/omega2/images/)
but I'm unable to create a usable image (like a VDI, say, using VBoxManage or the like) from those .bin files. Unsurprising.

Next I thought I might be able to create an image using dd by doing something like:
ssh root@omega.local "dd if=/dev/sda | gzip -1 -" | dd of=/tmp/image.gz
however, it doesn't look like the filesystem is at /dev/sda.

I'm relatively new to OpenWRT/LEDE but I know enough about linux to get myself in trouble. If anyone could help me out here I'd be very appreciative.

Thanks!

Could you describe how you were able to get the OS moved to USB? I've been trying to figure this out with no luck. Thank you.