DNS option not being used with DHCP (Mycroft II)

j1nx · November 18, 2022, 7:01pm

If the guys from pantacore use a squashfs which by design is read only, they most likely also use an OverlayFS to write to certain files.

/etc is heavily integrated within systemd so if systemd already touches/uses the file before the OverlayFS is mounted it can not be altered.

As systemd basically is “init” (/usr/sbin/init) which is the first thing that gets started by the kernel, you need to mount the overlay before init gets called.

In OpenVoiceOS i basically added a pre-init which mounts the overlayfs and then hands over the control to the systemd init.

See the WIP pre-init at below link;

github.com

OpenVoiceOS/ovos-buildroot/blob/develop/buildroot-external/rootfs-overlay/usr/sbin/pre-init

#!/bin/sh

set -euo pipefail

PATH=/sbin:/bin:/usr/sbin:/usr/bin

/bin/mount -t proc proc /proc
/bin/mount -t sysfs sysfs /sys
grep -w "/dev" /proc/mounts >/dev/null || /bin/mount -t devtmpfs none /dev

[ -z "${CMDLINE+x}" ] && CMDLINE=`cat /proc/cmdline`
for arg in $CMDLINE; do
	optarg=`expr "x$arg" : 'x[^=]*=\(.*\)' || echo ''`
	case $arg in
		root=*)
			ROOT_RODEVICE=$optarg ;;
		rootfstype=*)
			ROOT_ROFSTYPE=$optarg ;;
	esac
done

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I add the kernel cmdline parameter “init=/user/sbin/pre-init” to boot this pre-init which mount the overlayfs and then the normal init is started.

(Bare in mind the pre-init is still wip as i need to included the mirrored boot A/B logic to it for the update system later on)