Running with #overlayroot=tmpfs in /boot/uEnv.txt:

Warning: fsck not present, so skipping root file system
[   18.116608] EXT4-fs (mmcblk0p1): INFO: recovery required on readonly filesystem
[   18.124044] EXT4-fs (mmcblk0p1): write access will be enabled during recovery
[   18.165407] EXT4-fs (mmcblk0p1): recovery complete
[   18.173528] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode. Opts: (null)
done.



Running with overlayroot=tmpfs in /boot/uEnv.txt:

Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Running /scripts/local-premount ... Scanning for Btrfs filesystems
done.
Begin: Will now check root file system ... fsck from util-linux 2.36.1
[/sbin/fsck.ext4 (1) -- /dev/mmcblk0p1] fsck.ext4 -a -C0 /dev/mmcblk0p1
rootfs: clean, 28639/889024 files, 358032/3779579 blocks
done.
[   18.404928] EXT4-fs (mmcblk0p1): mounted filesystem with ordered data mode. Opts: (null)
done.
Begin: Running /scripts/local-bottom ... done.
Begin: Running /scripts/init-bottom ... Warning: overlayroot: configuring overlayroot with driver=overlay mode=tmpfs opts='' per kernel cmdline
Success: overlayroot: configured root with 'tmpfs' using overlay per kernel cmdline
done.
[   18.913855] Not activating Mandatory Access Control as /sbin/tomoyo-init does not exist.
[   19.578486] systemd[1]: systemd 247.3-7 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +ZSTD +SECCOMP +BLKID +ELFUTILS +KMOD +IDN2 -IDN +PCRE2 default-hierarchy=unified)
[   19.601933] systemd[1]: Detected architecture arm.