Ubuntu
linux package

  1. Bug #922037
  2. Comment #18

Comment 18 for bug 922037

Revision history for this message
Youquan Song (youquan-song) wrote : Re: "reduce brightness" key freezes system

This issue comes from broken BIOS SMI (like generated when you kick specifica keys etc) hang because it does not aware of OS in x2apic mode. So the workround way is to blacklist issued platform.

Yes. there are other T420 platforms have the issue (https://launchpadlibrarian.net/109393850/dmidecode.txt), so I tend to disable x2apic at all of T420 platforms.

Refer to bug reports:
https://bugzilla.kernel.org/show_bug.cgi?id=43054
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/776999

Please try the patches if it works on your T420.