In my early post, a cross build environment has been set up on a powerful AMD64 system to compile packages for the Raspberry Pi 3B. As mentioned, the cross build environment itself is a minimal Linux root system, in which armv7a-architecture packages are installed. However, how can those packages be available to the Raspberry Pi 3B? Thus, in this post I will continue to set up a binhost (binary package host) [1] on the AMD64 system, which aims to provide the Raspberry Pi 3B readily installable, precompiled packages.
Set up a Binhost on the AMD64 System
The first step is to generate binary packages whenever a package is installed by the portage system, which can be approached by the buildpkg feature in the "/etc/portage/make.conf" file:
$ sudo nano /etc/portage/make.conf
FEATURES="buildpkg"
Next step is to find a way of transfering binary packages from the AMD64 system to the Raspberry Pi 3B. Here is an example of using the SSH protocol to access binary packages:
# copy the public key of the Raspberry Pi 3B to the AMD64 system $ ssh-copy-id -i ~/.ssh/rpi3b USER@AMD64
Install Binary Packages on the Raspberry Pi 3B
Correspondingly, to let the portage system retreive binary packages while installing packages is to use the getbinpkg feature in the "/etc/portage/make.conf" file:
$ sudo nano /etc/portage/make.conf
FEATURES="getbinpkg"
Also, to tell the portage system to download binary packages through the SSH protocol from the AMD64 system:
$ sudo nano /etc/portage/make.conf
PORTAGE_BINHOST="ssh://USER@AMD64/usr/armv7a-unknown-linux-gnueabihf/var/cache/binpkgs"
After that, installing a package on the Raspberry Pi 3B will not compile the package from scratch, instead a pre-compiled binary package will be used:
$ sudo emerge -av <PKG>
Thanks for reading :)