mirror of
https://github.com/Dasharo/systemd.git
synced 2026-03-06 15:02:31 -08:00
The USB persist feature allows devices that can retain their state when powered down to work across suspend/resume. This is in particular useful for USB drives. However, the persist feature can get in the way for devices that are unable to retain their state when power is lost. An example of such stateful devices are fingerprint readers where USB persist should be disabled to ensure userspace can detect whether the USB device had a power loss during system suspend. This will initially be used by the libfprint autosuspend hwdb. Closes: #20754
Files in this directory specify a description of hardware devices, in the form of mappings from modalias-like keys (which identify specific hardware devices) to udev properties. Files in this directory are not read by udev directly. Instead, man:systemd-hwdb(8) compiles them into a binary database. See man:hwdb(7) for an overview of the configuration file format, and man:systemd-udevd.service(8) for a description of the udev daemon. Use 'systemd-analyze cat-config udev/hwdb.d' to display the effective config.