systemd systemd.image-filter 7 systemd.image-filter Disk Image Dissection Filter In systemd, whenever a disk image (DDI) implementing the Discoverable Partitions Specification is activated, a filter may be specified controlling which partitions to consider for mounting. Such a disk image dissection filter is a string that contains per-partition-type patterns, separated by colons (:). The individual rules consist of a partition identifier, an equal sign (=), and a shell globbing pattern applied to the GPT label string of the partition. See glob7 for details on shell globbing. The partition identifiers currently defined are: root, usr, home, srv, esp, xbootldr, swap, root-verity, root-verity-sig, usr-verity, usr-verity-sig, tmp, var. These identifiers match the relevant partition types in the Discoverable Partitions Specification, but are agnostic to CPU architectures. Various systemd components that support operating with disk images support a --image-filter= command line option to specify the image filter to use. If no filter is specified all partitions in partition table are considered and no per-label filtering is applied (except that partitions with the _empty label are always ignored). For the host root file system image itself systemd-gpt-auto-generator8 is responsible for processing the GPT partition table and making use of the included discoverable partitions. It accepts an image filter via the kernel command line option systemd.image_filter=. The following image filter string dictates that for the root file system partition only partitions shall be considered whose label begins with ParticleOS-. For the /usr/ partition the precise label ParticleOS_47110815 is required. root=ParticleOS-*:usr=ParticleOS_47110815 systemd1 systemd-dissect1 systemd-gpt-auto-generator8 systemd.image-policy7