Hi Lennart, > Which udevadm command is this from? The udevadm trigger invocation we > do during boot? This is a Yocto based build and the boot flow is using an initramfs. After setting up /sys /proc and other related specifics the initramfs calls $_UDEV_DAEMON --daemon udevadm trigger --action=add udevadm settle the _UDEV_DAEMON is set to /lib/systemd/systemd-udevd. This seemed to work just fine before enabling the kconfigs I mentioned in my initial report. > can you reproduce this if you trigger manually? If you strace, do you > see where the EIO comes from? I am generating a build where I can stop inside the initramfs to fiddle around with this. Using strace might be worth a try which I haven't done just yet. I'll give these a try and post back. Thanks a lot for the support here. BR, Awais