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.
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:/ /launchpadlibra rian.net/ 109393850/ dmidecode. txt), so I tend to disable x2apic at all of T420 platforms.
Refer to bug reports: /bugzilla. kernel. org/show_ bug.cgi? id=43054 /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/776999
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Please try the patches if it works on your T420.