Re: [PATCH 1/3] rtc-efi: register rtc-efi device when EFI enabled
Date: Tue Jan 01 2013 - 21:48:51 EST
æ äï2012-12-28 æ 15:44 -0800ïH. Peter Anvin æåï
> On 12/28/2012 12:49 PM, Matthew Garrett wrote:
> > On Fri, 2012-12-28 at 12:40 -0800, H. Peter Anvin wrote:
> >>> I suspect that what we *should* do looks like:
> >>> 1. If ACPI exports a Time and Alarm Device (ACPI000E) the use it;
> >>> 2. If ACPI exports an PC/AT device (PNP0B00/1/2) then use it(*);
> >>> 3. If we have an EFI RTC use it;
> >>> 4. Probe for a PC/AT RTC device.
> > In terms of ordering, 3 should probably come before 2 - but that depends
> > on us actually fixing the issues that are preventing some of these calls
> > from working. As far as wallclock time goes, EFI is going to be
> > available to us before we've parsed the DSDT to determine whether
> > there's any ACPI devices, so we'll almost certainly end up having to use
> > it at at least some point during boot. Otherwise, agreed.
> [Resending due to misconfigured tablet]
> 3 before 2 is exactly what is known to break on existing hardware (ASUS).
I didn't find the EFI RTC problem on Asus from google.
Could you please share what's the situation on ASUS hardware?
Thanks a lot!
> If anything, we should move to using the EFI RTC as a very last resort,
> i.e. 3 after 4. Ideally we should match Win8 behavior, but that would
> require someone mocking up different ACPI and EFI functions in a
> simulator and see how Win8 prioritizes things.
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