Small embedded systems typically don't need them. This removes about 16KB from the kernel binary size on ARM when configured out. Corresponding syscalls are routed to a stub logging the attempt to use those syscalls which should be enough of a clue if they were disabled without proper consideration.
Signed-off-by: Nicolas Pitre <[email protected]> diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig index ee3de3421f..00e6098e9a 100644 --- a/drivers/ptp/Kconfig +++ b/drivers/ptp/Kconfig @@ -6,7 +6,7 @@ menu "PTP clock support" config PTP_1588_CLOCK tristate "PTP clock support" - depends on NET + depends on NET && POSIX_TIMERS select PPS select NET_PTP_CLASSIFY help diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 62824f2fe4..b055aa1b6b 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -195,3 +195,13 @@ config HIGH_RES_TIMERS endmenu endif + +config POSIX_TIMERS + bool "Posix Clocks & timers" if EMBEDDED + default y + help + This includes native support for POSIX timers into the kernel. + Small embedded systems may have no use for them and therefore they + can be configured out to reduce the size of the kernel image. + If unsure say y. + diff --git a/kernel/time/Makefile b/kernel/time/Makefile index 49eca0beed..fc26c308f5 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -1,6 +1,12 @@ -obj-y += time.o timer.o hrtimer.o itimer.o posix-timers.o posix-cpu-timers.o +obj-y += time.o timer.o hrtimer.o itimer.o obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o -obj-y += timeconv.o timecounter.o posix-clock.o alarmtimer.o +obj-y += timeconv.o timecounter.o alarmtimer.o + +ifeq ($(CONFIG_POSIX_TIMERS),y) + obj-y += posix-timers.o posix-cpu-timers.o posix-clock.o +else + obj-y += posix-stubs.o +endif obj-$(CONFIG_GENERIC_CLOCKEVENTS) += clockevents.o tick-common.o ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y) diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c new file mode 100644 index 0000000000..879f37f6f3 --- /dev/null +++ b/kernel/time/posix-stubs.c @@ -0,0 +1,82 @@ +/* + * Dummy stubs used when CONFIG_POSIX_TIMERS=n + * + * Created by: Nicolas Pitre, July 2016 + * Copyright: (C) 2016 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <linux/kernel.h> +#include <linux/random.h> +#include <linux/errno.h> +#include <linux/posix-timers.h> + +asmlinkage long sys_ni_posix_timers(void) +{ + pr_err_once("process %d (%s) attempted a POSIX timer syscall " + "while CONFIG_POSIX_TIMERS is not set\n", + current->pid, current->comm); + return -ENOSYS; +} + +#define SYS_NI(name) SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers) + +SYS_NI(timer_create); +SYS_NI(timer_gettime); +SYS_NI(timer_getoverrun); +SYS_NI(timer_settime); +SYS_NI(timer_delete); +SYS_NI(clock_settime); +SYS_NI(clock_gettime); +SYS_NI(clock_adjtime); +SYS_NI(clock_getres); +SYS_NI(clock_nanosleep); + +void do_schedule_next_timer(struct siginfo *info) +{ +} + +void exit_itimers(struct signal_struct *sig) +{ +} + +void posix_timers_register_clock(const clockid_t clock_id, + struct k_clock *new_clock) +{ +} + +int posix_timer_event(struct k_itimer *timr, int si_private) +{ + return 0; +} + +void run_posix_cpu_timers(struct task_struct *tsk) +{ +} + +void posix_cpu_timers_exit(struct task_struct *tsk) +{ + add_device_randomness((const void*) &tsk->se.sum_exec_runtime, + sizeof(unsigned long long)); +} + +void posix_cpu_timers_exit_group(struct task_struct *tsk) +{ +} + +void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, + cputime_t *newval, cputime_t *oldval) +{ +} + +void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) +{ +} + +void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) +{ +}
