syscall.sh / nios2 / futex_wait

futex_wait

sys_futex_wait(void *uaddr, unsigned long val, unsigned long mask, unsigned int flags, struct __kernel_timespec *timespec, clockid_t clockid)

register	value
`r2`	455, the syscall number
`r4`	void *uaddr
`r5`	unsigned long val
`r6`	unsigned long mask
`r7`	unsigned int flags
`r8`	struct __kernel_timespec *timespec
`r9`	clockid_t clockid
`r2`	the return value

Then run trap to enter the kernel.

Same syscall on other architectures