TFD_CLOEXEC
uml_rtc_irq_fds[0] = timerfd_create(CLOCK_REALTIME, TFD_CLOEXEC);
BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
#define TFD_SHARED_FCNTL_FLAGS (TFD_CLOEXEC | TFD_NONBLOCK)
timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK);
eet->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC);