OpenEmbedded / Yocto Usage Survey
Recently, I sent a survey to the OpenEmbedded and Yocto mail lists asking a series of questions about how they use OE. 38 people responded. The average number of years using OE is 4.8 years.
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Rebasing a set of changes with Git
One of the common things we do during Linux kernel development is move a series of patches from one kernel version to a similar version (say Linux 4.1 to 4.1.12). This is required as new stable versions of particular kernel version are released. One approach is to merge, but then your changes are mixed in with upstream commits and are more difficult to manage. Git rebase offers a convenient way to move a set of patches. In the following example we have a series of changes we made (or patches we applied) on top of the 4.1 kernel.
Modifying the BusyBox config in OpenEmbedded
Recently, I needed to enable the eject command in BusyBox for an OpenEmbedded (Yocto) based project. Below is a way to do this in a fairly painless way:
- bitbake -c menuconfig busybox (enable the eject command in the config and save)
- bitbake -c diffconfig busybox (this generates a config fragment, note the fragment file location)
- recipetool appendsrcfile -w [path to layer] busybox [path to fragment generated in step #2]
Best practices for using CMake in OpenEmbedded/Yocto
I’ve already written about using autotools and qmake in OE. With recent projects, we’re using CMake to build most C/C++ components. Like any good tool, CMake has a learning curve, but it seems to do its job quite well. Below are examples of a CMake build file, and corresponding OE recipe.
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PCB Schematics Style Guide
As I work at the intersection of hardware and software, I spend a fair amount of time reading schematics for printed circuit boards (PCBs). I’m astounded at how sloppy most schematics are, and have come up with a few suggestions to consider.
Library sizes for C vs C++ in an embedded Linux system
Is the size of the libraries required for C++ (vs C) a concern in Embedded Linux systems? Most Embedded Linux systems likely include some C++ code, so this is probably not even a decision we need to make in many cases. However, often there is a need for a small initramfs that is used as part of the boot process (perhaps for software updates) before switching to the main root file system. In this case, it makes sense to keep the initramfs as small as possible, and we might be concerned here with the size of C++ libraries.
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Why systemd in Embedded Linux Systems?
Recently I was asked why use systemd vs sysvinit in embedded systems? There are many discussions on this, and really most of the reasons people use it for servers and desktops are also valid for embedded systems. Lennart Poettering’s articles explain very well why you might want to consider systemd. A few things that rank high on my list:
Setting up an OpenEmbedded Package Feed Server
With the BEC OE build template, you can easily set up an opkg feed server that serves up packages from your build directory. This allows… Read More »Setting up an OpenEmbedded Package Feed Server
OpenEmbedded Build Template
How does one set an OpenEmbedded/Yocto/Poky/Angstrom build? There are many options. Some include: Angstrom setup scripts Poky Freescale Community BSP OpenEmbedded core standalone (I’m sure… Read More »OpenEmbedded Build Template
OS Containers for Build Systems
Since I’ve been running archlinux on some of my systems, one thing I’ve found useful is systemd-nspawn. systemd-nspawn containers (or chroots on non-systemd systems) give… Read More »OS Containers for Build Systems