systemd-gpt-auto-generator: add option to specify additional devices to dissect

[b-]

I often use systems that have swap partitions on a different block device from the root filesystem, but I'd like to still benefit from systemd-gpt-auto-generator's detection of swap partitions. One use case example is a RAM-starved Chromebook with an eMMC and an SD slot. I use a partition on the eMMC for swap and the SD for rootfs, because the SD is larger and attached to a slower interface than the eMMC.

I see there already is a TODO entry to add an option to override the device, so I wanted to point at that as well. But the difference between that and my request is that I'd like to be able to specify multiple devices.

[poettering]

Sorry, but that makes no sense to me gpt-auto-generator really is about auto-probing things to cover the generic case. But if you want to configure some extra device, why bother with gpt-auto-generator?

If you have a specialist setup, that uses different devices for different explicit purposes, then just use /etc/fstab?