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Welcome to the 34th issue of TMPDIR Weekly, a newsletter covering Embedded Linux, IoT systems, and technology in general. Please pass it on to anyone else you think might be interested and send any tips or feedback to our forum or

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Yocto 4.0 LTS Released

Yocto's latest release codenamed 'kirkstone' came out with lot of changes of which some are not backward compatible, e.g. replacing override separate literal ( _ to : ) and many of the changes implement inclusive language related changes. License types have been improved to be more accurate e.g. BSD linceses are now specified with sub-categories e.g BSD-3-clause. All recipes now follow SPDX naming convention for LICENSE field. Reproducible builds are turned on by default. Here are migration notes which are quite handy when upgrading from a prior version of the project.

Yoe Distro switches to using usrmerge distro feature

usrmerge is denoting a file heirarchy where /bin and /lib etc. are merged into their /usr counterparts. This ensures that /usr contains everything that a base OS needs and thusly can be made read-only or manupulated easily for other kind of policies. There have been extensive debates about it in various Linux distribution communities. OpenEmbedded has made this as a feature which is not turned on by default but can cleanly switch distributions to use it. The Yoe distro has started using this feature and 2022.04 will be first release to use this feature. Further, we would like to use read-only rootfs with r/w overlay from /data partition, this will help in ensuring that OS remains immutable and can be factory resetted easily, but also give flexiblity to have config files kept peristent over OS upgrades, since in Yoe we use the Yoe updater which does full system upgrades.


Simple IoT v0.0.45 has been released. This version includes NATS API improvements, store and view app and OS version in root node, package upgrades, and addition of a user auth NATS API.


Caddy v2.5.0 has been released. The release notes mention Tailscale integration, which is interesting.

Quote for the week

Documentation is the castor oil of programming. Managers think it is good for programmers and programmers hate it!. - Gerald Weinberg

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Thanks for reading!

Khem and Cliff