From d4d1fc61eb38ff8e5af657e2d2f2290859a277f2 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Tue, 31 Oct 2017 10:43:39 -0700 Subject: ia64: Update fsyscall gettime to use modern vsyscall_update John Stultz provided the outline for this patch back in May 2014 here: http://patches.linaro.org/patch/30501/ but I let this sit on the shelf for too long and in the intervening years almost every field in "struct timekeeper" was changed. So this is almost completely different from his original. Though the key change in arch/ia64/kernel/fsys.S remains the same. The core logic change with the updated vsyscall method is that we preserve the base nanosecond value in shifted nanoseconds, which allows us to avoid truncating and rounding up to the next nanosecond every tick to avoid inconsistencies. Thus the logic moved from nsec = ((cycle_delta * mult)>>shift) + base_nsec; to nsec = ((cycle_delta * mult) + base_snsec) >> shift; Cc: John Stultz Cc: linux-ia64@vger.kernel.org Signed-off-by: Tony Luck --- arch/ia64/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/ia64/Kconfig') diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 6a15083cc366..4d032e7f1637 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -46,7 +46,7 @@ config IA64 select ARCH_TASK_STRUCT_ALLOCATOR select ARCH_THREAD_STACK_ALLOCATOR select ARCH_CLOCKSOURCE_DATA - select GENERIC_TIME_VSYSCALL_OLD + select GENERIC_TIME_VSYSCALL select SYSCTL_ARCH_UNALIGN_NO_WARN select HAVE_MOD_ARCH_SPECIFIC select MODULES_USE_ELF_RELA -- cgit v1.2.3