Re: [yocto] Building recipes in multiple flavors for differing images

[Alexander Kanavin <alex.kanavin@gmail.com>]

I'm afraid the correct approach to this is indeed several distros.
Yocto, by design, does not support building the same item several
times in a single bitbake invocation.

What you can do, is take a long hard look at the specific differences
between the distros, and see what you can unify. There's probably a
few decisions there that made sense before, but don't fulfil a need
anymore. For example, do you really need the debug/release builds? Can
you standardize on systemd everywhere? Can you make decisions about
logging and other choices at runtime rather than at build time?

And so on.

Alex

On Thu, 28 Apr 2022 at 11:09, Martin Weber
<martin.weber@br-automation.com> wrote:
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> Hi everybody!
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> We use yocto to build the system for some of our devices. Given we have multiple use-cases for differing partitions on the device (rescue system; main system in “release” flavor; main system in “development & debug” flavor), we use different custom distros for our build.
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> With this mail we would like to ask the community what the best practice for our use case are, describe our current approach, and ask whether we can do things in a better way.
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> The software we use (machine/bsp layer level; software level) in principal is the same (same upstream, internal or 3rd party), but we need to build them in different ways (e.g., one uses system V init, one uses systemd init; one uses optimized-non-logging versions of the software, another ships debug symbols and enables logging during buildtime; one installs and enables various systemd units, another doesn’t, etc.).
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> Our solution to this problem is that we have (three) different distros, and use distro overrides to enable/disable/patch/append/delete various bits and pieces throughout the otherwise shared recipes. The “problem” with this is that we need to use different build environments to build our three distros, i.e., we cannot re-use otherwise identical packages. We were wondering whether it would be possible to use three images instead, and build the recipes in differing ways depending on the image. The “cleanest” way we could think of to do this would be to use recipe.inc files for the basic setup of each recipe, and recipe-X.bb, recipe-Y.bb, recipe-Z.bb that customize the build for the various use cases. This works fine for recipes that we control, but we stumble over customizing re-used recipes from lower layers that way. For example take dropbear; we might want to enable or disable it by default depending on the use case; and build with or without systemd integration. We can’t find a clean way to extend the recipe in the upper layer with, say, dropbear-sysv.bb, dropbear-systemd-disabled.bb, dropbear-systemd-enabled.bb because then we don’t extend the underlying dropbear.bb; if we require/include the underlying recipe, we have a different $PN and now the FILES(EXTRA)PATH won’t resolve properly (and all $PN overrides in dropbear.inc don’t apply). If we force the original $PN, now we’re building the “same” package three times..
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> Once more, we do have a working solution for this (use different build directories and different distros) that enable re-use of the base recipes (we use .bbappends to customize lower-layer recipes with OVERRIDEs in that scenario) and were mostly wondering whether there’s a /c?leaner/ approach with more (CPU-cycle, harddisk space and package DB) re-use.
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> Thanks in advance for any input & Best regards,
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> Martin Weber
> Research & Development – Embedded Software Engineer
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> B&R Industrial Automation GmbH, B&R Straße 1, 5142 Eggelsberg, Austria, www.br-automation.com
> Phone +43 7748 6586 - 0
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