time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons
authorJohn Stultz <john.stultz@linaro.org>
Wed, 24 Apr 2013 18:32:56 +0000 (11:32 -0700)
committerThomas Gleixner <tglx@linutronix.de>
Tue, 14 May 2013 18:54:06 +0000 (20:54 +0200)
commitb4f711ee03d28f776fd2324fd0bd999cc428e4d2
tree8d8b659c2514648be0bfe51f0de65110da008f22
parent42a5cf46cd56f46267d2a9fcf2655f4078cd3042
time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons

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.

Reported-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: stable <stable@vger.kernel.org> #3.9
Cc: Feng Tang <feng.tang@intel.com>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Link: http://lkml.kernel.org/r/1366828376-18124-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
arch/x86/Kconfig
drivers/rtc/Kconfig
include/linux/time.h
kernel/time/Kconfig