Lennart, Is it not possible for a udev rule like the following to work? MYVAR has been imported (with value sda) and is visible for the block device. I verified it with udevadm info --query=name -x sda. KERNEL=="%E{MYVAR}", TAG+="test" The end result is that this rule doesn't fire. Could someone explain why? According to the man pages, I think this should work. Kind Regards, Kevin -----Original Message----- From: Lennart Poettering <lennart@xxxxxxxxxxxxxx> Sent: Monday, January 13, 2020 10:54 AM To: Boyce, Kevin P [US] (AS) <Kevin.Boyce@xxxxxxx> Cc: systemd-devel@xxxxxxxxxxxxxxxxxxxxx Subject: Re: EXT :Re: Systemd udev add tag for boot device On Mo, 13.01.20 09:10, Boyce, Kevin P. (AS) (kevin.boyce@xxxxxxx) wrote: > Thank you Lennart. > > I'm thinking I will create my own sort of "built-in" command that can > parse /proc/cmdline to look for the root= variable early in udev rules > so I can create the tag. So, systemd has to for determining the backing file system of some directory and this is used by gpt-auto-generator for finding the block device backing / or /usr/. I figure you want something like that? We don't expose that directly though, and it's limited, since we do not cover complex storage. We do cover btrfs though. Lennart -- Lennart Poettering, Berlin _______________________________________________ systemd-devel mailing list systemd-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/systemd-devel