Re: [PATCH 1/2] rtc/ia64: remove legacy efirtc driver

From: Arnd Bergmann
Date: Fri Oct 25 2019 - 06:42:09 EST

On Thu, Oct 24, 2019 at 6:57 PM Luck, Tony <tony.luck@xxxxxxxxx> wrote:
> > arch/ia64 has a read_persistent_clock64() function, so it ends up reading
> > the system time regardless of the RTC driver or CONFIG_RTC_HCTOSYS.
> >
> > As ia64 sets neither ARCH_HIBERNATION_POSSIBLE nor
> > ARCH_SUSPEND_POSSIBLE, so we could just remove the
> > read_persistent_clock64() and efi_gettimeofday(), relying instead
> > on user space (/sbin/hwclock) or CONFIG_RTC_HCTOSYS.
> Seems weird. ia64 has always assumed from day 1 that it is running
> on a UEFI capable platorm (well at day 1 it was called "EFI", the "U"
> came later).
> So read_persistent_clock64() just calls EFI directly to get the time.
> Seems simpler than worrying about having the right drivers and CONFIG
> bits set.

It would just be a little more consistent. Most architectures cannot
implement read_persistent_clock64() or CONFIG_RTC_HCTOSYS
when the RTC driver is a loadable module, so distros normally have to
set the system time after loading modules already. If some architectures
have a reliable platform interface that allows setting the time at early
boot, that doesn't mean we have to rely on that.