04-27-2018 12:20 AM - last edited on 06-04-2018 05:20 AM by Andy_Lenovo
The T480s has a bug in the ACPI tables.
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 at 65 Celsius).
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 - as of UEFI v1.11)
The changelog for the UEFI update v1.11 makes explicit mention of this bug:
"<1.11> UEFI: 1.11 / ECP: 1.07
-(Fix) Fix an issue where system may become hot by system interrupts when Thundrebolt is disabled in ThinkPad Setup - Security - I/O Port Access."
Unfortunately, the bug still exists while thunderbolt is "enabled" in UEFI settings.
I believe I have found the specific code that is causing this bug, as well as the solution.
I would like to get in touch with a Lenovo engineer in order to help them resolve this issue.
Admin note; subject edited for relevancy
Solved! Go to Solution.