Hi,

I notice that when booting with DTS UEFI will disable RTC device PL031
in the DTS by following codes. And it turns out that only rtc-efi shows
up in guest.

//
// UEFI takes ownership of the RTC hardware, and exposes its functionality
// through the UEFI Runtime Services GetTime, SetTime, etc. This means we
// need to disable it in the device tree to prevent the OS from
attaching its
// device driver as well.
//
if ((RtcNode != -1) &&
    fdt_setprop_string (DeviceTreeBase, RtcNode, "status",
        "disabled") != 0) {
  DEBUG ((EFI_D_WARN, "Failed to set PL031 status to 'disabled'\n"));
}

But when booting with ACPI, there are two RTC devices, rtc-efi and
PL031(PL031 shows up when kenrel PL031 driver adds support to probe it
via ACPI). And I didn't see any codes in UEFI to handle the RTC node in
ACPI table.

I think it's hard to modify the DSDT table in UEFI since there is not a
ACPI lib like libfdt. But for consistency, does it need to handle it too
when booting with ACPI?

Thanks,
-- 
Shannon

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