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    SubjectRe: [PATCH 1/3] rtc-efi: register rtc-efi device when EFI enabled
    On 12/28/2012 11:17 AM, Matthew Garrett wrote:
    > On Fri, 2012-12-28 at 11:07 -0800, H. Peter Anvin wrote:
    >> We do have such machines, which is why this change has been reverted twice already. I believe we should stick to the priority scheme I proposed a few weeks ago.
    >
    > I seem to have missed that discussion, and couldn't find it after a
    > brief search. Got a pointer?
    >

    Looks like it was a non-public distribution ... anyway, what I wrote was:

    > 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.
    >
    > I'm unsure what the ordering of 1 & 2 should be. The ACPI device has
    > the advantage that it contains time zone information, which is important
    > for Windows interoperability, and at least optionally supports
    > millisecond resolution; there is no way to even export "this is where
    > you find time zone information" (since we're dealing with an RTC with
    > embedded CMOS, there is storage available, it is just a matter of
    > telling the OS how to find it) for the PNP0B0x devices.
    >
    > The TAD is also guaranteed to map 1:1 to the EFI RTC.
    >
    > -hpa


    --
    H. Peter Anvin, Intel Open Source Technology Center
    I work for Intel. I don't speak on their behalf.



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