From 9094c72c3d81bf2416b7c79d12c8494ab8fbac20 Mon Sep 17 00:00:00 2001 From: Anna-Maria Behnsen Date: Mon, 19 May 2025 10:33:20 +0200 Subject: time: Introduce auxiliary POSIX clocks To support auxiliary timekeeping and the related user space interfaces, it's required to define a clock ID range for them. Reserve 8 auxiliary clock IDs after the regular timekeeping clock ID space. This is the maximum number of auxiliary clocks the kernel can support. The actual number of supported clocks depends obviously on the presence of related devices and might be constraint by the available VDSO space. Add the corresponding timekeeper IDs as well. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Acked-by: John Stultz Link: https://lore.kernel.org/all/20250519083025.905800695@linutronix.de --- include/uapi/linux/time.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/time.h b/include/uapi/linux/time.h index 4f4b6e48e01c..16ca1ac206fd 100644 --- a/include/uapi/linux/time.h +++ b/include/uapi/linux/time.h @@ -64,6 +64,17 @@ struct timezone { #define CLOCK_TAI 11 #define MAX_CLOCKS 16 + +/* + * AUX clock support. AUXiliary clocks are dynamically configured by + * enabling a clock ID. These clock can be steered independently of the + * core timekeeper. The kernel can support up to 8 auxiliary clocks, but + * the actual limit depends on eventual architecture constraints vs. VDSO. + */ +#define CLOCK_AUX MAX_CLOCKS +#define MAX_AUX_CLOCKS 8 +#define CLOCK_AUX_LAST (CLOCK_AUX + MAX_AUX_CLOCKS - 1) + #define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC) #define CLOCKS_MONO CLOCK_MONOTONIC -- cgit v1.2.3