“This bug deserves more attention than it is currently receiving. It should be pinned in every forum with an affected machine, so that owners of those machines will be aware that it exists. It is currently squirreled away in the T series forum, under the outdated title “T480s – ACPI bug”. I have asked that the title be updated and received no response, which is why I’m posting this here.[…]
There’s a bug in the ACPI tables that affects all of the machines listed in the title. The bug causes heavy CPU usage on one thread due to frequent ACPI interrupts. The symptoms are a slow system, and high CPU temperatures (idles around 65 degrees Celsius). Some operating systems may mitigate the symptoms, but the bug is present regardless.
The following circumstances trigger it:
-powering on the laptop
-waking from suspend (and possibly hibernate – untested)
The following actions prevent it:
-reboot the laptop (temporary fix)
-disable thunderbolt in the UEFI settings (permanent fix – with latest UEFI updates)
The official UEFI update changelogs for all of these machines make explicit mention of this issue: “-(Fix) Fix an issue where system may become hot by system interrupts when Thundrebolt is disabled in ThinkPad Setup – Security – I/O Port Access.”[…]
https://forums.lenovo.com/t5/ThinkPad-T400-T500-and-newer-T/T480s-ACPI-bug/m-p/4064963#M124889
https://forums.lenovo.com/t5/ThinkPad-T400-T500-and-newer-T/T480s-ACPI-bug/m-p/4067181#M124936
https://download.lenovo.com/pccbbs/mobiles/n22ur05w.txt
Firmware Security 