For users having non-English, and especially non-qwerty layouts, using the host
shell can be very awkward. There was no option to change the keymaps as they
haven't been installed in the OS, and the persistence couldn't have been
achieved because of read-only /etc.
With upstream patch merged in #4224, we have an option to put
/etc/vconsole.conf to a writable location and use the same approach as in the
timezone PR. This is needed because even if we only bind-mounted the file from
the overlay directory, the Systemd services which start early will still refer
to the inode on the read-only FS. Also, gzip is required as current version of
kbd in Buildroot (v2.6.4) always compresses the keymaps using gzip. We can get
rid of this after we bump to kbd v2.9.0 [1] or newer. The overall bloat in
local build of the OS is slightly over 1 MiB, so it is acceptable.
With these changes, the `localectl set-keymap` command can be used to use any
available keymap from the installed `kbd` package (refer to `localectl
list-keymaps` for complete lists) and persist it between reboots.
[1] https://github.com/legionus/kbd/releases/tag/v2.9.0Fixes#1775
To make system timezone configurable, we need to have /etc/localtime
writable, and it must be possible to atomically create a symlink from
this place, which means the whole parent folder must be writable. We
don't have /etc writable and can't use the usual bind mount for this.
Latest Systemd v258 has patch that allows setting an environment
variable that sets where the localtime should be written. This can be
persisted in the overlay partition, with a symlink from /etc/localtime
leading there, finally pointing to the actual zoneinfo file. If the
symlink doesn't exist, create it by hassos-overlay script (it's not
really needed as UTC is the default, but Systemd does the same if you
change from non-UTC timezone back to UTC).
Also disable BR2_TARGET_LOCALTIME, so /etc/localtime and /etc/timezone
(the latter is only informative and non-standard) are not written by the
tzdata package build.
