timerfd_settime

timers that notify via file descriptors

sys_timerfd_settime(int ufd, int flags, const struct __kernel_itimerspec *utmr, struct __kernel_itimerspec *otmr)

register	value
`a7`	86, the syscall number
`a0`	int ufd
`a1`	int flags
`a2`	const struct __kernel_itimerspec *utmr
`a3`	struct __kernel_itimerspec *otmr
`a0`	the return value

Then run ecall to enter the kernel.

Same syscall on other architectures