Ok, autoreply.
I finally found compiled packages on LEDE proyect , arch is mipsel_24kc.
https://downloads.lede-project.org/releases/packages-17.01/mipsel_24kc/packages/

Sorry for the noise. Let this thread be for announcing cross-compiling instructions was for Onion I only.

Regards.

I'm talking about Omega2+, I've just realized instructions are for first Omega. I cannot find that architecture on menuconfig. Is there another way to cross-compile? I've only have to compile a pair o pacakges, not the whole firmware.

Hi there.
I've cross-compiled OpenWRT sources for a couple of packets, following the wiki instructions for configuration and build, then got my *_ar71xx.ipks aparently correct. Then copied to Onion but opkg refused to install alleging alien architecture.
A list of supported architectures show:

arch all 1
arch noarch 1
arch mipsel_24kc 10

That surprised me as ar71xx was not even mentioned. So I added it manually to opkg.conf:

arch ar71xx 100

And opkg accepted them as spected, --force not even necessary, but the installed binaries don't work. They seem not recognized as binaries
and executed as shells:

root@Omega-ZZZZ:~# mybin
/usr/bin/mybin: line 1: syntax error: unexpected end of file
root@Omega-ZZZZ:~# rmybin2
/usr/bin/mybin2: line 1: syntax error: unexpected ")"

So binary architecture seem not correct. what I'm doing wrong?

Thanks.