Replacing Yocto with Guix kernel image builds: best practices

[Trevor Lee <begleybrothers@gmail.com>]

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Hi,
We are now looking to build Linux kernels using Guix instead of Yocto.  We
can't see any reason why the builds wouldn't be linux-libre. Ideally we'd
like our effort to be accepted by upstream guix.

However, being new to Guix we are still coming grips with the best
practice(s) for what we would like to do.
We've looked at Guix's linux.scm, and
Efraim Flashner's post[1] is our primary reference - many thanks Efraim.

We'd appreciate any pointers to package definition(s) that demonstrate best
practices to do what we'd like:

- We'd like to build custom configured kernels for each patch series in the
LTS 4.14.72+, 4.19+ and 5.4+.
- Currently we have two `base` kernel configs that each 'variant'
configuration is applied to for each of a machine 'type' (3 machine types)
and one of two 'arch'.
- Currently we can generate a full kernel `.config` for a
kernel+base+variant+arch (we are working on the best way to handle
different machines if we are not using Yocto.)
- We'd ideally like to generate `vmlinux`, `initrd` and `rootfs` images for
each.

Based on Efraim's post we think the first example is the least friction -
"including an actual .config file as a native input to our custom kernel".
Assume we resolve the machine definition issue.  However we're puzzled
about how to best distribute the configuration file such that a build of
kernel x.y.z can be updated with fixes.
The constraint of users being able to use the std guix commands rather than
telling them to download a config file or clone a git repo and copy a
config file is what is puzzling. Some options we thought about seem
inelegant - hence too embarassing to mention - so we'll skip them ;)
Leaving....

1) We did wonder if channels[2] were the way to go with each kernel x.y.z
in its own branch and config files therein. Could anyone point us to
packages that setup and use package specific channels?
2) Should we be aiming to provide a single package with multiple parameters
or is it better to provide a package for each kernel x.y.z, or some other
partitioning. We'd likely want to script the package definition then -
correct?

Appreciate any comments suggestions or tips.

[1]:
https://guix.gnu.org/blog/2019/creating-and-using-a-custom-linux-kernel-on-guix-system/
[2]: https://guix.gnu.org/manual/en/guix.html#Channels

-- 
Kind Regards

Begley Brothers Inc.


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