Orange Pi Plus2

Intro
The Orange Pi Plus2 (http://www.orangepi.org/orangepiplus2/) is one of the most powerful boards of the Orange Pi line of products. It carries 2Gb RAM and an USB-SATA bridge, therefore allowing the connection of classical HDDs to it.

A variant named Orange Pi Plus 2E (http://www.orangepi.org/orangepiplus2e/) is supposed to have a better performance and more stability. However, it lacks the SATA interface and carries 3 USB 2.0 ports instead of 4.

The GPIO header on both boards is much similar to the one found on Raspberry Pi but one shall take into account that the header is rotated 180 degrees on the 2E model.

Both models work relatively well under an implementation of Gentoo for a IoT/server environment (no graphics tested, no video, GPIO intensively used). The only frequent issue are hangouts during long and highly intensive use of the board, however, they are not as frequent as with the Raspberry Pi. Anyway, building a system from stage3 on these boards is NOT recommended. Package building and upgrading may not be so troublesome as with the RPi family but there is a clear exception to such large builds like gcc, glibc or llvm. So, the best way to create and support a Orange Pi Plus2 Gentoo implementation is to cross-compile, which can be quite difficult. However, there is a plus - the main difference between Plus2, the Plus2E and probably some other boards is miserable. In most cases one needs only to choose the correct Device Tree Blob (DTB) file in the boot sequence. So, if one manages to create a cross-compile environment for one Orange, probably that will fit for other models.

With some changes, the cross-compile environment can be used on Raspberry Pi 2 boards (it was successfully tested here).

Initial remarks
Most data to implement a Gentoo system was taken from:

1. http://linux-sunxi.org/Xunlong_Orange_Pi_Plus_2

2. http://linux-sunxi.org/Xunlong_Orange_Pi_Plus_2E

3. https://wiki.gentoo.org/wiki/Raspberry_Pi

4. https://wiki.gentoo.org/wiki/Cross_build_environment

However, there are several critical issues that do not allow to follow the above instructions by the letter. The most important - avoid all about kernel version 3. It will bring more trouble using such versions than to build a kernel 4.15 or higher. Even if taken from a ready build, most 3.* kernels look far from being stable on the Orange platform.