Comment 12 for bug 1951586

On the subject of crda being deprecated, the situation appears to be as follows:

* The "iw" application, more specifically the "iw reg set" command will continue to operate as normal, but (as before), this is an ephemeral setting that will need re-setting on every boot

* The "/etc/default/crda" file will no longer be available as a persistent store of the regulatory region

* The formerly deprecated "cfg80211.ieee80211_regdom" kernel command line argument was at some point re-enabled to act as if "iw" (or some other userspace application) were configuring the region. Thus, it could be used as a (rather hacky) means of persisting the region

For example, on the Pi, in lieu of any other solution, I'll likely be recommending that people add "cfg80211.ieee80211_regdom=GB" (or the appropriate country code) to "/boot/firmware/cmdline.txt".

The assumption from the kernel side seems to be that persisting this is "something for the desktop to handle", which seems pretty sensible given that one of the queries in almost any desktop setup (including ours) is "where are you?" from which we derive the timezone but could equally derive the regulatory region (I note we don't currently appear to -- perhaps this bug should affect ubiquity too?).

Obviously, however, that doesn't deal with things like the server images. Personally, I think this only bolsters the case for adding the configuration to netplan or cloud-init. Unless we want to add a separate mechanism for persisting the regulatory domain, and then have to ensure that it is set sufficiently early that whatever wifi configuration is performed by netplan/cloud-init is done with the correct regulatory domain in force?