[systemd-devel] systemd blocks update kernel partition table

[Lennart Poettering]

On Mi, 21.11.18 23:26, e-stl at gmx.de (e-stl at gmx.de) wrote:

>    Hi list,
>    i'm new to systemd and are working with an embedded device with yocto.
>     
>    In my embedded device i want to format and store my emmc device with the
>    new firmware. When updating the firmware the device boots from SD card.
>     
>    When updating the firmware i want to (re)partition my emmc storage device
>    with parted and 3 ext4 partitions. None of the partitions is mounted,
>    because the device boots from SD card.
>    When the emmc already contains a partition table parted complains that it
>    can't update the kernel partition table after it was modified.
>    It seems these partitions are already mounted anywhere. partprobe doesn't
>    help either.
>     
>    But i don't mount them and when i check for mounted partitions by mount
>    command, none of them is mounted. The only thing i see is that systemd has
>    created device units for these partitions. In syslog i see that the ext4
>    partition is recognized (also in /sys/fs/ext4 available). I assume that
>    the systemd device units block the update of the kernel partition
>    table.

.device units are just a representation of devices reported by
udev/kernel in the systemd "unit" concept. PID 1 never actually opens
them, it just tracks them. And it hence is not keeping them busy.

>    I need to modify, format and fill the partitions on the emmc without
>    booting after the new partition table is written.
>     
>    My question is: What/is systemd blocking the update of the kernel
>    partition table and what can i do to prevent it?

I doubt it is. It must be something else.

Use fuser or a similar tool to figure out what is keeping it busy.

Lennart

-- 
Lennart Poettering, Red Hat