diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2014-07-16 23:05:12 +0200 |
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committer | John Stultz <john.stultz@linaro.org> | 2014-07-24 00:01:51 +0200 |
commit | 09ec54429c6d10f87d1f084de53ae2c1c3a81108 (patch) | |
tree | 842749293edd755e8bb12e1433c2f9df7dd842cf /arch/x86/Kconfig | |
parent | clocksource: Make delta calculation a function (diff) | |
download | linux-09ec54429c6d10f87d1f084de53ae2c1c3a81108.tar.xz linux-09ec54429c6d10f87d1f084de53ae2c1c3a81108.zip |
clocksource: Move cycle_last validation to core code
The only user of the cycle_last validation is the x86 TSC. In order to
provide NMI safe accessor functions for clock monotonic and
monotonic_raw we need to do that in the core.
We can't do the TSC specific
if (now < cycle_last)
now = cycle_last;
for the other wrapping around clocksources, but TSC has
CLOCKSOURCE_MASK(64) which actually does not mask out anything so if
now is less than cycle_last the subtraction will give a negative
result. So we can check for that in clocksource_delta() and return 0
for that case.
Implement and enable it for x86
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'arch/x86/Kconfig')
-rw-r--r-- | arch/x86/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7fa17b5ce668..d08e061c187a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -109,6 +109,7 @@ config X86 select CLOCKSOURCE_WATCHDOG select GENERIC_CLOCKEVENTS select ARCH_CLOCKSOURCE_DATA + select CLOCKSOURCE_VALIDATE_LAST_CYCLE select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC) select GENERIC_TIME_VSYSCALL select GENERIC_STRNCPY_FROM_USER |