linux-kernel - Re: [PATCH] rtc: Disable EFI rtc for x86

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Date:	Tue, 11 Nov 2014 07:14:15 -0500
From:	Austin S Hemmelgarn <ahferroin7@...il.com>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	"H. Peter Anvin" <hpa@...or.com>
CC:	Matthew Garrett <mjg59@...f.ucam.org>,
	Pali Rohár <pali.rohar@...il.com>,
	Matt Fleming <matt.fleming@...el.com>,
	Borislav Petkov <bp@...en8.de>,
	Mark Salter <msalter@...hat.com>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	rtc-linux@...glegroups.com, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Dave Young <dyoung@...hat.com>
Subject: Re: [PATCH] rtc: Disable EFI rtc for x86

On 2014-11-11 06:38, One Thousand Gnomes wrote:
>>> look further into the options I have set in my kernel build, I may have
>>> changed something else without remembering between booting with and
>>> without the CSM enabled.
>>>
>>
>> It could also be that the non-CSM BIOS somehow remaps the CMOS registers.
>
> I don't believe there is anything which prevents the CSM from faking a
> CMOS clock using SMM from whatever is actually in the hardware.
>
> Alan
>
It wouldn't surprise me if that were the case.  I've had some pretty 
weird firmware related issues with other Lenovo systems before (like the 
brightness hot-keys causing the reported trip points for ACPI thermal 
zones to temporarily change).

I've rebuilt the kernel I'm using with everything I can think of 
possibly depending on the CSM compiled out or as modules, so I'll 
hopefully have some more info soon.


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