This is beautiful. Deterministic, bootstrapped, and doesn't break the established Linux conventions! Shame it's musl-only, I would love to use something like that to build glibc-based apps for future redistribution as proper Linux binaries.

I've generally found buildroot work pretty well. One common problem causing weird issues however is lots of tools from the host system are used (without any sandboxing). E.g building old releases of buildroot on newer Ubuntu will break.

Its biggest Achilles heel IMO is the need to always compile everything from scratch with no possibility of caching. Also the fact that incremental rebuilds after changing config options isn't guaranteed to work unless you manually know to know which packages to force nuke and force to recompile (this is intentional design choice for implementation simplicity and well documented). Also having two different boards that inherit from common shared config isn't really supported, everyone just rolls their own custom config splicer at that point.

Yocto fixes those issues, but IMO the most other things are much less ergonomic. While buildroot is extremely simple, yocto is total opposite to that, an architecture astronaut's dream. There is custom language to learn, ton of functionality, config and documentation split in tiny files in different repositories. Of which everyone using slightly different subset to accomplish almost the same thing.

> It uses the kernel's `make menuconfig` system which seems like it occupies a bad place between "easy usable GUI" and "robust config file you can check in to git".

Are you aware you can generate a sparse config file with `make savedefconfig`? Maybe you're aware of that and it doesn't meet your definition of robust, which is reasonable.

I think Buildroot is much better engineered than Yocto, in the sense of simplicity. Buildroot is fundamentally just a bunch of make and kconfig. Yocto has some powerful features but I find it to be considerably more difficult to penetrate "what is actually happening here". I haven't had as negative an experience with Buildroot error messages, but if you think those are bad, Yocto errors are like g++ template errors circa 2010.

I found the learning curve to be much easier with buildroot and compared to yocto whose build system is python but uses mixed shell/python to describe the build.

Builroot errors seemed to happen much less, and easier to understand compared to Yocto errors. Also seemed easier to corrupt the Yocto environment to the point of having to wipe and start fresh

Buildroot kconfig and TUI menuconfig was super simple to find and add packages to the rootfs, even custom ones patched in to tree to out of tree directories that could be added in with a config option.

Yocto AFAICT does not have a package discovery via TUI. You have to guess at package names, add them to you config and wait for build error to say not found. It will at least sometimes recommend similar named packages or the actual package name that eg provides the library you wanted. Otherwise it’s a search on openembedded to find package recipes that are not in the Yocto poky reference.

Adding OOT tree code to Yocto is pretty simple, once you figure out to write shell/python recipe

The makefile/Kconfig way of buildroot seemed much more intuitive especially given the kernel, busybox and uboot all use kconfig. So if you’re used to those, buildroot just seemed a natural extension to the rootfs.

I wonder if one day we'll see Zig used for system development. Among its other peculiarities, it also use itself as build language.

https://ziglang.org/learn/build-system/

I've previously developed a commercial product that used buildroot.

In that case, it used an A/B partition layout like Android, along with a custom update script and kernel-based bootloader to implement atomic updates and fallback capability. The rootfs image was built by buildroot and devices would query an API and download the image, then write it to the inactive root partition.

You can do effectively the same thing with GRUB, but the project I worked on also supported devices that booted using u-boot. The kexec bootloader allowed a single implementation for different architectures and platforms.

So, the answer is you can update however you want, but there are a few common ways it's done in embedded.

At work I've developed a buildroot based "embedded OS" för intel machines. Our buildroot system gets bundled into the kernels initramfs and we boot straight into that from UEFI. For upgrades we kexec() into a new kernel-image so generally we never write anything to disk (The original image can still be upgraded if deemed necessary). All applications are then regular docker images. All this is managed by an in-house developed deamon. Works quite well. That said, we're not really using buildroot for anything other than building a few libs + this in-house daemon so I'm leaning towards getting rid of it and just rely on busybox+musl+a few other deps built using a simple script.

It's sort of out of the scope of Buildroot, but there are different systems like mender or swupdate that cover updates. They tend to need some level of platform specific changes because embedded systems these days have 7 levels of bootloaders.

Well, buildroot is mainly for embedded applications, so whatever applies to that: OTA updates with A/B partitioning are common. OStree-based are getting a lot of traction as well.

But technically you could build something with a package manager etc and update as usual. It's just a build system.

I would love to know. I currently have an embedded product using buildroot and as it is not exposed to a network at all, I don't have any worries about security. However, I'd love to hear of a nice mechanism to basically upgrade the system image in place. I imagine you could use something like a pair of partitions and just change the kernel boot parameters to point at the most recent one, but I'm curious about what solutions people use.

You build a new filesystem image and apply the new filesystem to the system.

Not very sophisticated to use a throwaway account to advertise your product.