This is a copy of the original blog post here, as a precaution against the link going dead. I've added a few of my own notes that I found helpful.
If you own a Lenovo X1 6th generation and want to use Linux, you're not going to be happy from the start. The entire range of hardware works splendidly and almost out of the box (let alone the fingerprint reader), but Lenovo decided to make one major change in the new UEFI firmware image. They removed traditional deep sleep (ACPI S3 sleep state) in favor of a new, Microsoft-driven sleep state called Windows Modern Standby, aka Si03. This sleep state doesn't fully turn off all components except for main memory, but puts the devices themselves into an ultra low-power state. This way, much like modern smartphones do, some devices can briefly wake up particular components of the system - most notably communication devices. The idea is, to have an always-connected feature, to e.g. downl