On Wed, Aug 14, 2019 at 6:48 PM <h...@zytor.com> wrote: > > I believe Windows 10 changed the default RTC to UTC, although perhaps > only if running under UEFI.
I looked at the efi rtc driver now, and found two things: - The EFI get_time() call passes down timezone information, so we know what UTC is, and can just ignore the timezone. This is good. - The RTC_DRV_EFI depends on !X86 as of commit 7efe665903d0 ("rtc: Disable EFI rtc for x86"). This unfortunately means we always fall back to either the rtc-cmos driver or the x86 specific read_persistent_clock64() implementation even when the EFI RTC is reliable. If 64-bit Windows relies on a working EFI RTC implementation, we could decide to leave the driver enabled on 64-bit and only disable it for 32-bit EFI. That way, future distros would no longer have to worry about the localtime hack, at least the ones that have dropped support for 32-bit x86 kernels. Arnd