Re: [PATCH] time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile timeoptimizaitons

From: Feng Tang
Date: Thu Apr 25 2013 - 02:33:15 EST

On Wed, Apr 24, 2013 at 11:32:56AM -0700, John Stultz 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.
> While the udev rules could use some work to be less fragile,
> breaking userland should strongly be avoided. Additionally
> the compile time optimizations are fairly minor, and the code
> being optimized is likely to be reworked in the future, so
> lets revert this change.
> I suspect this will miss 3.9-final, so marking it for 3.9-stable.


Acked-by: Feng Tang <feng.tang@xxxxxxxxx>

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