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

Austin S Hemmelgarn
2014-11-10T20:37:46Z

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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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