.device units wait for udev to broadcast the uevent about that device being added, which happens after udev has 1. received the initial kernel uevent (either real or produced by systemd-udev-trigger.service) and 2. finished processing all its .rules for that device (which means everything that rules launched from RUN= must have exited, etc).
Only devices that udev rules have tagged with TAG+="systemd" will produce .device units; generally 99-systemd.rules will add that to disk devices.
If any of the rules have marked the device with ENV{SYSTEMD_READY}="0", the .device unit will keep waiting until another event removes that.
On Sat, Sep 16, 2023, 07:54 Philip Couling <couling@xxxxxxxxx> wrote:
I'm trying to understand what a system is timing out waiting for a device in /etc/fstab when a simple "mount -av" will succeed.To reach systemd, initramfs has already mounted the device as the base layer to an overlay mount used as the root file system, so it's definitely ready to use in the Linux kernel. In /etc/fstab, fsck is set to 0.What condition does systemd wait for that could be timing out on a device that's already mounted?
