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ThinkTank480
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Posts: 31
Registered: ‎04-26-2018
Location: CA
Views: 15,326

FYI - Linux May Not Support Thunderbolt Native Mode

Hello,

 

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.

 

Thanks!

 

Admin note; subject edited for relevancy

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