Re: [PATCH] time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons

From: Kay Sievers
Date: Wed Apr 24 2013 - 14:41:35 EST

On Wed, Apr 24, 2013 at 8:32 PM, John Stultz <john.stultz@xxxxxxxxxx> wrote:
> Kay Sievers noted that the ALWAYS_USE_PERSISTENT_CLOCK config,
> which enables some minor compile time optimization to avoid
> uncessary code in mostly the suspend/resume path could cause
> problems for userland.
> In particular, the dependency for RTC_HCTOSYS on
> !ALWAYS_USE_PERSISTENT_CLOCK, which avoids setting the time
> twice and simplifies suspend/resume, has the side effect
> of causing the /sys/class/rtc/rtcN/hctosys flag to always be
> zero, and this flag is commonly used by udev to setup the
> /dev/rtc symlink to /dev/rtcN, which can cause pain for
> older applications.

FWIW, in the light of the original change, I've just removed the
/dev/rtc creation from the default udev rules now, so that thing will
be phased out in the future.

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