HAL deprecated, replaced by udev
HAL (Hardware Abstraction Layer) is deprecated. It is replaced by udev. HPLIP uses HAL to mark HPLIP-supported printers as having the scanner capability so that HAL opens access to their low-level USB device files (/dev/bus/usb/*/*) for the user currently logged in to the desktop.
Now udev rules have to take over this responsibility. For that upstream udev has now the rule
HPLIP now only need to mark the supported devices with its own udev rules, for example with rules like this:
The complete 40-hplip.rules is attached.
Can you ship these rules with HPLIP? They will work for all distributions as the new rule in 70-acl.rules is already implemented in udev upstream.