I recently stumbled upon HypriotOS while looking for Docker-ready distributions for my Raspberry Pi 3B+. I flashed this onto and SD card and started playing around with it. It works incredibly well, but I noticed that it was built for armv7l which is a 32-bit implementation. Since the Raspberry Pi 3B+ has a 4x core Cortex-A53 which is 64 bit, I wanted to make use of the 64 bit processor! I’ve worked with Yocto before (in fact, my day job uses Yocto), so I decided I’d build my own. For more on containers, see my other blog posts on what it is, what it can be used for, and how to use it.

Process

Prerequisites

Yocto is a build, not a distribution, so it is quite resource intensive. I would suggest having at least 60GB free disk space, and a quad core machine at a minimum. You’ll also need a Linux installation, and the build essentials installed (git, gcc, etc.).

EDIT: Checking the disk usage after the builds shows around 55GB used. On a 2C4T Intel Core i5 it took about 2H to build.

Project Setup

First, create a working directory and clone all the piece-parts we need to build.

mkdir rpi3bplus-build-yocto
cd rpi3bplus-build-yocto
git clone git://git.yoctoproject.org/poky
git clone git://git.openembedded.org/meta-openembedded
git clone git://git.yoctoproject.org/meta-raspberrypi
git clone git://git.yoctoproject.org/meta-virtualization 

Next create the project and add the base layers.

source poky/oe-init-build-env rpi64
bitbake-layers add-layer ../meta-raspberrypi
bitbake-layers add-layer ../meta-openembedded/meta-oe
bitbake-layers add-layer ../meta-openembedded/meta-python
bitbake-layers add-layer ../meta-openembedded/meta-perl
bitbake-layers add-layer ../meta-openembedded/meta-networking
bitbake-layers add-layer ../meta-openembedded/meta-filesystems
bitbake-layers add-layer ../meta-virtualization

Edit the conf/local.conf file sections as needed:

MACHINE ??= "raspberrypi3-64"
CORE_IMAGE_EXTRA_INSTALL += "kernel-modules htop openssh iperf3 docker-ce bash ntp "

INHERIT += "extrausers"

EXTRA_USERS_PARAMS += " useradd pi; \
                       usermod  -p 'raspberry' pi; \
                       usermod  -a -G sudo pi; \
                       usermod -P root root; "

DISTRO_FEATURES_append = " virtualization"

Next we will build the image. This will take a while depending on how beefy your build machine is.

bitbake core-image-minimal
Parsing recipes: 100% |########################################################################################################################################################################################################| Time: 0:02:16
Parsing of 2540 .bb files complete (0 cached, 2540 parsed). 3827 targets, 140 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION           = "1.44.0"
BUILD_SYS            = "x86_64-linux"
NATIVELSBSTRING      = "universal"
TARGET_SYS           = "aarch64-poky-linux"
MACHINE              = "raspberrypi3-64"
DISTRO               = "poky"
DISTRO_VERSION       = "3.0"
TUNE_FEATURES        = "aarch64 cortexa53 crc"
TARGET_FPU           = ""
meta                 
meta-poky            
meta-yocto-bsp       = "master:6bb4a252199cfd5d44ad7ab6fc4118c80a1aae92"
meta-raspberrypi     = "master:a0a5d3848e76b7f90ef8e42c56211da78db1c7ba"
meta-oe              
meta-python          
meta-perl            
meta-networking      
meta-filesystems     = "master:d9f3e6dbed8e5d96f2069280f0a566af89afb2fa"
meta-virtualization  = "master:5fb77ae4c4e1015e40257f9e59e16c497e30c53c"

After a couple of hours, you will have a completed, ready to flash SD Image at <build>/rpi3bplus-build-yocto/rpi64/tmp/deploy/images/raspberrypi3-64/core-image-minimal-raspberrypi3-64.rpi-sdimg which you can burn to an SD card with:

dd if=./core-image-minimal-raspberrypi3-64.rpi-sdimg of=/dev/sdX status=progress

Your image should boot up and docker will be running!

NOTE: You will manually have to set the date to pull from Docker registries over HTTPS because the certification validation will fail otherwise. We could add and configure NTP to fix the but… for another day. Use:

date "+%d-%m-%C%y %H:%M:%S" -s "2019-12-22 00:30:01"

There is one last thing you’ll want to do. You’ll want to use GParted or similar tool to enlarge your filesystem partition to take up the rest of your SD card so you will have some room for container images. You need to do this because the default SD Image builder script only provides enough space for the root filesystem and no more. In my configuration it ended up being ~300MB, so I expanded it take up the remaining ~59GB. See example below:

Results

As it turns out, I have a system that can build and run 64-bit Docker images and is pretty darn slim. Here’s a screenshot of htop running.. only 12 processes – not bad!

Some Metrics

The is the minimal image and it has 12 processes, with an incredibly low footprint. I loaded up an Ubuntu container and installed iperf3, then ran a test to my laptop. I was impressed to find the following result:

[ ID] Interval           Transfer     Bandwidth       Retr
[  5]   0.00-10.13  sec   116 MBytes  96.0 Mbits/sec    9             sender
[  5]   0.00-10.13  sec   113 MBytes  93.8 Mbits/sec                  receiver

Even running that test, the load on the Pi was:

root@raspberrypi3-64:~# cat /proc/loadavg 
0.05 0.22 0.19 1/141 2125
root@raspberrypi3-64:~# 

Downloads

The post Building a Customized Linux Image for Raspberry Pi with Yocto + Docker Support appeared first on Jacob N Calvert.

apropos

This utility is related to the man utility. You can use it to find references within manual pages simply by providing an argument that is close to or exactly what you are looking for. For example you can find all the manual page names and sections that relate to printf simply by invoking apropos printf. This will give you results for printf, fprintf, vprintf, vfwprintf… and so on.

cat

This one is one of my most used and extremely useful. Issuing cat FILENAME and the contents of that file will be dumped to the screen. Easy peasy.

dig

This is a handy little network utility. You can use it to grab information about any domain by simply running dig some.example.com any.

find

Here is an extremely useful command. Ever need to know where a file is in the structure but only remember its name? find . -name filename will find it for you.

last

Another simple but useful command. Lists the last users logged into the system with times and other info.

look

In most Linux distros, you can look up the spelling of an English word without breaking out the dictionary. Suppose you don’t know how to spell “superfluous.” Type look superfl and you will see a list of words beginning with “superfl” — including superfluous.

nc

nc or netcat is a TCP and UDP utility that can act as a listener/receiver as well as a requester/sender/server. There are so many options with this one that you’re better off checking the man page.

nl

This short command stands for “numbered lines.” Give it a file name as a parameter and it will print the file with numbered lines. Pretty useful!

pstree

Issuing this guy will print out a formatted tree of the processes on the system.

tail

This is useful for debugging. My most common usage is this: tail -f /var/log/some.log. That will open the log file and continually print the last few lines so you can debug that service.

touch

You can do a lot of things with touch, but the most basic is file creation. Need a new file right here? touch FILENAME. Done.

tree

Similar to pstree but with the filesystem.

wget

Download all the things! The wget command will aloow you to download resources from a server simply by doing wget http://some.server.com/resource.ext. Check out the man page for all the other amazing features of wget.

which

If you want to know what binary (or alias) is called when you issue a command, you use which SOME_COMMAND. You’ll find out what you want to know.

who

If you want to know the users logged into the system, issue who.

whoami

If you’re feeling lost, or simply forgot if you’re root or whoever, whoami will tell you right away.

This list is far from exhaustive, because frankly, there are so many great utilities in most flavors of Linux, but these are some of my favorites. I’ve linked each one to their respective man pages below.

apropos
cat
dig
find
last
look
nc
nl
pstreetail
touch
tree
wget
which
who
whoami

Thanks for reading!

The post Useful Linux Commands appeared first on Jacob N Calvert.