Re: [PATCH] rtc: Disable EFI rtc for x86

From: Austin S Hemmelgarn
Date: Mon Nov 10 2014 - 15:37:49 EST


On 2014-11-10 12:04, Matthew Garrett wrote:
On Mon, Nov 10, 2014 at 11:45:06AM -0500, Austin S Hemmelgarn wrote:

I agree, without it you need PC CMOS RTC support to access the RTC
on most systems, which in turn means that you have to enable the CSM
in the EFI firmware, which is annoying cause you can't easily dual
boot windows with secure boot when the CSM is enabled.

CMOS RTC support doesn't depend on the CSM.

That's really interesting, because with it compiled in, I can't boot on my EFI based thinkpad laptop without telling EFI to launch the CSM, and with it compiled out, I can boot fine without the CSM. I'll have to 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.

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