Comment 0 for bug 2069834

Debian systemd now mounts a tmpfs on /tmp by default; relevant d/changelog entry:

systemd (256~rc3-3) unstable; urgency=medium

   * Make /tmp/ a tmpfs by default. Restore the upstream default and make
    /tmp/ a tmpfs. Can be overridden with: touch
    /etc/systemd/system/tmp.mount or: systemctl mask tmp.mount

Ubuntu is aligning to this, however this means that available space under /tmp is limited to the half of the available ram. That is sometimes not enough to unpack source trees in /tmp, see for example [1].

We need to to decide how to deal with this. Possibilities I can think about:

1. Disable the tmpfs tmp.mount, as suggested in the d/changelog entry. To be done in setup-testbed. Good: easy. Bad: deviates from the Ubuntu defaults, requires rebuilding the images.

2. Make autopkgtest use /var/tmp. Good: we stick to the defaults: Bad: requires non trivial changes in src:autopkgtest, which makes assumptions on stuff being in /tmp, on /tmp being cleared on reboots, ...

This under the assumption that the switch to a tmpfs has been discussed, and we want it in Ubuntu.

[1] https://autopkgtest.ubuntu.com/results/autopkgtest-oracular/oracular/ppc64el/c/ceph/20240618_194813_d6efc@/log.gz