linux-kernel - ACPI enable on Thinkpad X60 hangs when temperatures are high

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Message-ID: <20190527103155.GB12391@xo-6d-61-c0.localdomain>
Date:   Mon, 27 May 2019 12:31:55 +0200
From:   Pavel Machek <pavel@....cz>
To:     kernel list <linux-kernel@...r.kernel.org>, tglx@...utronix.de,
        bp@...e.de, hpa@...or.com, mingo@...hat.com, x86@...nel.org,
        rjw@...ysocki.net, lenb@...nel.org, linux-acpi@...r.kernel.org
Cc:     pavel@....cz
Subject: ACPI enable on Thinkpad X60 hangs when temperatures are high

Hi!

> > So if you compile a kernel, then reboot, boot will hang after "Freeing SMP
> > alternatives memory" (and then wastes power, making thermal situation even worse).
> 
> Normally, next message is "smpboot: CPU0: Genuine Intel...".
> 
> I added some printks, and check_bugs() returns. Then it goes to ACPI and never
> comes back...
> 
> kernel-parameters.txt points to Documentation/acpi/debug.txt, but that one does not exist.
> 
> Any ideas what debugging parameters to use for ACPI? I either get nothing or
> so much that machine does not boot...

I ended up adding printks...

It hangs in acpi_hw_set_mode().

ACPI enable: set mode: acpi
ACPI: hw_set_mode
ACPI: hw_set_mode mode switch
ACPI: write_port?
ACPI: os write port

we write to the port but that never returns.

I assume SMM is doing its magic at that point. Any ideas how to debug it further?

Is it possible that it is some kind of screaming interrupt?

										Pavel


-- 
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