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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5461FD97.1080601@gmail.com>
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.


Download attachment "smime.p7s" of type "application/pkcs7-signature" (2455 bytes)